01 13 Formatting with Printf
Summary
TLDRThis educational video script introduces the 'printf' method in Java, which is used for formatted output. It explains the use of special characters like %s for strings, %d for integers, and %c for characters, with a focus on %f for floating-point numbers, particularly for displaying monetary values with two decimal places using %.2f. The script also demonstrates how to align text in columns using printf, emphasizing the importance of spacing and formatting for clear and organized output. It concludes with tips on using printf for common programming tasks, such as printing integers and characters, and the necessity of including a newline character for proper display.
Takeaways
- 📝 **Printf Introduction**: The video introduces printf as a method for formatting output in Java, similar to print and println but with enhanced formatting capabilities.
- 🔡 **Special Characters in Printf**: It explains the use of special characters like %s for strings, %d for integers, %c for characters, and %f for floating-point numbers in printf statements.
- 💵 **Formatting Money**: One of the primary uses of printf is to format money, ensuring that floating-point numbers display two decimal places, which is crucial for financial representations.
- 🔢 **Floating-Point Formatting**: The script demonstrates how to use %f and %.2f to control the number of decimal places displayed, with %.2f being particularly useful for money formatting.
- 📊 **Column Alignment**: Printf is used to align text in columns, which is helpful for creating tables or lining up data in a readable format.
- 🔠 **String Padding**: The video shows how to use printf to pad strings with spaces to ensure they occupy a specific number of characters, enhancing the visual structure of the output.
- 🔄 **Left and Right Alignment**: It discusses how to adjust the alignment of printed values within their designated spaces, either to the left or right, using negative or positive numbers in the printf format.
- ⏏️ **New Line Character**: The script points out that printf does not automatically add a new line, and %n must be used if a new line is desired after the printf statement.
- 🔧 **Eclipse Assistance**: The video mentions that the Eclipse IDE can assist in writing printf statements by autocompleting parts of the code, which can be both helpful and sometimes intrusive.
- 🔑 **Common Printf Uses**: The key takeaways highlight that %f is frequently used for monetary values, %s for columnar data, and %d for integer values, making these the most common formatting specifiers for beginners.
Q & A
What is printf and how does it differ from print and println in Java?
-Printf is a method used in Java for formatted output, similar to print and println, but it allows for better control over the formatting of the output. Unlike print and println, which print raw output and automatically add a newline respectively, printf requires specific formatting characters to control the output's appearance.
What are the special characters used in printf for formatting?
-Special characters used in printf for formatting include %s for strings, %d for integers, %c for characters, and %f for floating-point numbers. These characters are placeholders that tell printf how to format and display the variables that follow in the method call.
How can printf be used to display currency with two decimal places?
-Printf can be used to display currency with two decimal places by using the %f formatting character followed by '.2', which specifies that two decimal places should be shown. This ensures that the output is formatted to display money correctly, such as 1.70 instead of 1.7.
Why is it necessary to format floating-point numbers when displaying currency?
-Floating-point numbers should be formatted when displaying currency because financial transactions typically require two decimal places for cents. Java's default double representation might not show trailing zeros, which can lead to incorrect representations of currency amounts.
How does printf handle the alignment of text in columns?
-Printf handles the alignment of text in columns by using the %s formatting character followed by a number that specifies the width of the column. The text is then right-aligned within that width by default. To left-align the text, a negative sign is placed before the width number.
What is the purpose of using a newline character in printf?
-The newline character, represented by ' ', is used in printf to create a new line after the formatted output. Since printf does not automatically add a newline like println, it is necessary to include this character if a new line is desired after the output.
Can you provide an example of how to use printf to display a variable with a specific width?
-Yes, to display a variable with a specific width in printf, you would use the formatting character for the variable type followed by the desired width. For example, '%-15s' would left-align a string in a 15-character wide field.
How does printf handle spaces in the formatted output?
-Printf handles spaces in the formatted output by padding the remaining space in the specified width with spaces. For example, if a string is shorter than the specified width, printf will add spaces to the right (or left, if negative width is specified) to fill the field.
What is the difference between using printf and print or println for displaying columns of data?
-Printf allows for more precise control over the alignment and width of columns, making it easier to create neatly aligned tables of data. Print and println do not provide this level of control and can result in misaligned columns if not carefully managed with manual spacing.
How can you force printf to print a new line at the end of the output?
-You can force printf to print a new line at the end of the output by including the newline character ' ' at the end of the format string. Alternatively, you can use the '%n' escape sequence, which is platform-independent and will work across different systems.
Outlines
💻 Introduction to printf Formatting
This paragraph introduces the concept of using printf in Java for better formatting of output compared to print and println. It explains the use of special characters within printf to format strings, integers, and characters. The paragraph demonstrates how to use %s for strings, %d for integers, and %c for characters. It also discusses the common use of printf for displaying currency with two decimal places using %f, which is crucial for financial formatting where trailing zeros are significant. An example is given where a double variable representing money is formatted to show two decimal places, ensuring the correct display of currency.
📊 Formatting Columns with printf
The second paragraph delves into using printf for creating formatted columns. It explains how to use %s to specify the width of a string in a column and how padding works with spaces. The paragraph provides an example of aligning strings and integers in columns using printf, where the width of each column is defined by the programmer. It also touches on the use of newline characters in printf statements to separate rows of data, contrasting printf with println which automatically adds a newline. The paragraph concludes with a demonstration of how to adjust column alignment to the left by using a negative sign in the formatting string.
🔢 Advanced printf Formatting Techniques
Paragraph three builds on the previous discussion by showing how to mix integers and strings in columns using printf. It illustrates how to format an integer with a specified number of spaces and a string with a different specified width, aligning them neatly in columns. The paragraph also explains how to force a new line after each printf statement to separate data entries visually. Additionally, it covers the concept of right and left alignment within columns, showing how to adjust the formatting to push values to the right or left within a specified column width. The paragraph emphasizes the importance of consistent formatting for data presentation.
📝 Summary of printf Usage in Java
The final paragraph summarizes the key points covered in the video script regarding the use of printf in Java. It highlights the importance of %f for formatting monetary values with two decimal places, %s for aligning text in columns, and %d for printing integers. The paragraph reiterates that printf does not automatically add a newline at the end of a statement, so the programmer must include %n if a newline is desired. It wraps up by emphasizing the practical applications of printf for beginners in programming, particularly for tasks like formatting currency and creating neatly aligned columns of text.
Mindmap
Keywords
💡printf
💡formatting characters
💡%s
💡%d
💡%c
💡%.2f
💡variable
💡columns
💡right alignment
💡newline
Highlights
Introduction to printf as a method for formatted output in Java.
Explanation of special characters used in printf for formatting output.
Use of %s for string formatting in printf.
Utilization of %d for formatting integer values in printf.
Introduction of %c for character formatting in printf.
Demonstration of printf for displaying monetary values with two decimal places using %f.
Clarification on how printf handles floating-point numbers and the significance of %f.
Explanation of %f with a specific example of money formatting.
Use of printf to format and display variables within a string.
Tutorial on aligning columns using printf with %s and specified width.
Example of using printf to create formatted columns with strings and integers.
Discussion on how to force a new line after printf output.
Technique to left-align text in printf columns using negative width values.
Practical application of printf for creating neatly aligned columns in output.
Summary of the most commonly used printf formatting characters: %f for money, %s for columns, and %d for integers.
Emphasis on the importance of manually adding a new line with %n in printf statements.
Transcripts
okay in this video we're going to work
with print F and print F work with
printf printf is another method just
like print line and print in system dot
out but it allows you to format your
output better than print and print line
thus the print F so there are some
special characters you need to know
inside a printf for it to be used so I'm
gonna create maybe a header right here
I'm gonna kind of follow this one down
right and I'm gonna type some of these
characters that we're gonna use at first
and we're gonna build upon them as we go
so I'm gonna use % s right first which
is for a string I'm gonna use % d for an
integer decimal right integer and what
else are we gonna use at the beginning
maybe a % C for our character right
these are the basics right for our
character char right okay so let's talk
about how print F works if I have a
variable like int or let's use a double
or a double money and I assign it a
value like 1.7 one of the most commonly
used things inside a printf is when you
need to display money and here's why
let's say I was going to print that
amount of money out using a print line
so I say system dot out dot print line
use
and then I'm gonna put a dollar sign
right and then I'm gonna append money to
it and then I'm gonna say you know at my
store right so what's this gonna do this
is gonna print out you spend you know a
dollar seventy with a dollar sign at my
store so if I run this code right I
would get this now we can all tell that
this doesn't look right why doesn't it
look right it doesn't look right because
we don't display money as 1.7 we display
it as 1.7 Oh
however for floating point numbers or
for doubles even if I put the 1.70 there
right and and run it it's still gonna do
a dot 1.7 because the troweling zeros
aren't needed and java knows this right
in doubles so sometimes it's useful to
print out money that has two places
after the decimal point right so let's
see how we can do this so up here I'm
gonna add another one because I started
with money right I'm gonna come up and
say percent half for floating point
right float or double right okay so what
we can do is we can use a printf and we
use it almost the same way we say system
dot out dot print F right now eclipse is
gonna help you out it's going to put
self in there I'm gonna delete that for
now now the way pronounced work is we
put a quote with something in it right
and then we follow it with as many
variables as we want we don't mix quote
with variable with more quotes like we
do in print line we put everything we
want up here in the quotes and then we
put comma variable come a variable come
a variable come a variable depending on
how many variables there all right now
in this case there's only one so what
I'm gonna do inside the quotes is I'm
gonna write you spend and I'm gonna put
a dollar sign all right and then I'm
gonna leave a space for now at my store
all right and then I'm gonna put comma
and the variable I want printed right
money okay now I need to tell the printf
where in this string where in this
string I want the value of money to be
displayed and I want it to be displayed
right here right after that power sign
right so what I'm gonna use is my
special formatting characters which are
up here percent as percent d % c % F
right now % F is a floating point number
now the floating point number takes some
characteristics I could say % point 2f
now let's explain what % point 2f meets
% point 2f means I want to use two
decimal places after the decimal place I
want two values printed after the
decimal place regardless of how many
values there are so if there were a
hundred values after the decimal place
let's say I had one point seven nine six
four two it's only gonna print the first
two right I could also put a number
before the decimal point like five and
that's gonna use five spaces before the
decimal point no matter how big the
money is but for money I don't care how
many are used before it I can just let
that be whatever it is so % point 2f is
one of the most commonly used formatting
to print money so it's gonna take this
value of money and it's gonna fill it in
right here right where that percent F is
% point 2f and it's gonna use the
formatting which says put two spaces
after the decimal point
so if I run this now now I can see that
my second line the one that uses the
pronoun
used 1.70 now let's just make some
changes here if I used 0.4 F then what's
gonna happen it's gonna fill with 4 0 4
values after the decimal point right so
clearly 0.2 F is the way that we want to
display money okay
let's say we were going to display
columns again remember we were doing
columns right so we could use strings
for columns so what could I do instead
of trying to line things up I could use
print apps so let's we'll leave our
money example right cuz that's not a bad
example and then we're gonna declare
let's declare some values right I could
declare a couple integers into x equals
equals 5 int y equals 100
then let's declare some string string 1
s1 equals you know hello and string s2
equals goodbye right okay okay so now I
have some strings so now let's use those
so let's assume I wanted those to be
displayed in some columns so I could use
print line right and I can put column 1
and then column 2 but we went down this
road before that I have to figure out
how to put spaces in between all the
others right and it gets very confusing
right so what I could do is I could do
this printf okay so let's see how we
would use a print F instead of print
line I'm going to use printout now print
off again takes a quote with all our
formatting in here
then it's followed by the variables we
want printed the variables or strings or
any or values right so what I can do is
I can use % s appear and I could say I
want I want 15 characters ask something
using his first string so I want 15
characters in a string right and then I
want the second column to be I don't
know we can make it whatever we want we
can make it 15 also I could make it 12
for any 12s and then I want it to print
so I'm gonna put comma and I don't have
variables for column 1 and column 2 so
I'm just gonna put those strings column
1 and the next thing I want printed is
column - so let's dissect what I did in
this line so printf takes this first
formatting this first string is
formatting right so then it takes after
the Komet takes whatever's first here
column 1 and it puts it into the first
formatting here so it's going to use 15
columns to print column 1 and then it
takes the second thing passed in and it
puts it into the second formatting so
it's going to use 12 columns Supreme
column 2 so it's padding it with spaces
just like the point 2f padded with zeros
because it was a half a floating-point
number percent s is gonna pad with
spaces so if I just ran this code the
way it is I would get the line that says
column 1 and column 2 and they would the
first one would be using 15 characters
and the second would be let's put a new
line in between here so printf is like
print it's not like print line it does
not put a carriage return at yet so you
have a couple ways to do that I could
put in between these I could do system
dot out dot print line right and type
that or I could use special character up
here just like in print and print line
we have backslash on
in print F we have percent and actually
backslash and it also works but it's
better to keep it consistent with
percents so now this first line with the
money is going to have a carriage return
at the end so it won't all be on one
line so let's run this okay so now let's
look at this column 1 column 2 it used
15 spaces to print column 1 and if you
notice right let's count right to be
sure right I'm gonna count 1 2 3 4 5 6 7
8 9 10 11 12 13 14 15 right so it used
15 spaces to fill column 1 and padded
with spaces at the beginning and then it
used 12 spaces to do column to it right
so if I count these I've got 1 2 3 4 5 6
7 8 9 10 11 12
right so use 12 spaces to use those and
then I would like to force a new line at
the end so now let's see how we could
line up the next lines right so I could
use another printf and eclipse is
filling it sometimes when eclipse fills
things in it's really useful and
sometimes when eclipse fills things in
it gets in the way but I'll let you
decide that so now let's say I wanted to
print one of the numbers and one of the
strings in each comes socom one will be
my numbers and column 2 will be my
strings so the first thing I want to
print again using 15 spaces is an
integer which we use D for that four
decimal would be that I agree it would
be better with an eye but it is not okay
and then the second column is going to
be a string so I'm going to use percent
s but I wanted to use 12 spaces for that
right and then I'm gonna print a new
line
now the first value I want to be filled
in to this decimal is my axe and the
second value that I want to be filled in
to my string is my s1 so I'm going to
put comma X comma s 1
I'm gonna run this and if I see what
happens when I run it my columns line up
really nicely now because I'm forcing
the first come to be 15 the second
column to be 12 and again it's padding
these at the left-hand side it's padding
at the left-hand side so now let's say I
want my second set of values I could
copy this line right and I could pass in
Y and s2
right and now everything's gonna line up
nicely because my print F forces each
column to be 15 characters for com1 and
forces all column twos to be 12
characters right so it's easy to line up
now sometimes we may want to that when
when we print this out this is called
right alignment right or a right
adjustment it's forcing all the values
to the right hand side of the column
right because column one starts over
here on the left and ends after the one
so the five is right formatted right
it's with formatting it to the right and
the hundred is pushed to the right I can
push to the left also right I can push
the left also and the way I do that is I
put negative sign in front of the
formatting so let's just warm at the
left the first column to be left
adjusted right so I'm gonna use
negatives on the first columns
formatting and if we run this now right
now I see column one is left formatted
right and if I wanted the other columns
to be left adjusted right I could use a
negative sign there also right and if I
run it now it's all left adjusted so
it's padding the spaces to the right
right it's padding it out to 15 here
it's padding it out to 15 right here
it's okay so so the ones you're most
likely going to be used using the most
the first one you're going to use the
most
is the percent F and it's for money and
% point 2f is the most commonly used
reason for print F in your beginning
programming because you don't want money
to be to be displayed as one point seven
you want it to be displayed as one point
seven zero so % point 2f takes care of
that percent s is very useful for
columns as you saw right we we line up
columns right percent D is incredibly
important because typically we're
printing out integers right and then
percent F or sorry percent C for
characters we can pad those spaces out
again this is a general introduction to
printf a couple things to remember
printf is like a print statement it does
not put a new line at the end you have
to put the % n at the end of the string
if you want a new line to appear after
the print F ends
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