Standard I/O Functions – printf()

Without specifying any display formatting, the printf() function will use DEFAULT setting:

Print in a field of minimum length, beginning on the current position on the current line.

Standard I/O Functions – printf()

Example:

printf(“%s”, “Value of variable “);

printf(“%c”, ‘a’);

printf(“%s”, “ is: “);

printf(“%f\n”, 1.25);

printf(“%s%c%s%f\n”, “Value of variable”,’a’,” is: “, 1.25);

Output

Value of variable a is: 1.250000

Value of variable a is: 1.250000

Note that the element is printed starting from the last space of element printed earlier.

Standard I/O Functions – printf()

Format Specifier Minimum field

%d, %ld, number of digits that form the decimal

Example:

15 – 2 spaces, 1500 – 4 spaces

-15 – 3 spaces, -1500 – 5 spaces

Standard I/O Functions – printf()

Format Specifier Minimum field

%x, %X number of digits that form the hexadecimal

Example

4 (1 space – 4)

40 (2 spaces – 28)

-4 (8 spaces – fffffffc)

-40 (8 spaces – ffffffd8)

Note that when it is a negative number, 8 spaces are used.

Standard I/O Functions – printf()

Format Specifier Minimum field

%c 1

%f number of digits that form the integer part 1 space for decimal point

6 digit for fractional part

Example

1.25 (8 spaces – 1.250000)

11.23 (9 spaces – 11.230000)

Standard I/O Functions – printf()

Format Specifier Minimum field

%s Depends on number of characters

Example: “Hello, World!” (13 spaces – Hello, World!)

Standard I/O Functions – printf()

Consider this example:

printf(“I am %5d years old\n”, 28);

I a m 2 8 y e a r s o l d

5 spaces are reserved for the decimal number

Right Alignment - spaces at right side will be used first

Standard I/O Functions – printf()

Consider this example:

printf(“I am %5d years old\n”, 28);

I a m 2 8 y e a r s o l d

5 spaces are reserved for the decimal number

Right Alignment - spaces at right side will be used first

Standard I/O Functions – printf()

What’s the output?:

for (i = 0; i < 20; i += 5)

printf(“%2d x %2d = %3d\n”, i, i, i *i);

5 x 5 = 2 5

0 x 0 = 0

1 5 x 1 5 = 2 2 5

1 0 x 1 0 = 1 0 0

Output

Standard I/O Functions – printf()What’s the output?:

printf(“%8s5s\n”,”Decimal”,”Hex”

for (i = 10; i < 16; i ++)

printf(“%8d%5X\n”, i, i);

D e c i m a l H e x

1 0 A

1 1 B

1 2 C

1 3 D

1 5 E

1 6 F

Standard I/O Functions – printf()

Consider this example:

printf(“%-8s%-5s\n”, “Name”,”Age”);

N a m e A g e

%-8s - 8 spaces are reserved for string

‘-’ sign signify left alignment

%-5s - 5 spaces reserved for string left alignment

Standard I/O Functions – printf()

What’s the output?:

printf(“%-8s5s\n”, ”Decimal”, ”Hex”);

D e c i m a l H e x

Output

Standard I/O Functions – printf()

Consider this example:

printf(“RM %8.2f\n”, 388.88888);

%8.2f - 8 spaces are reserved for the floating point number where 2 of the spaces are for the fractional/precision part.

Right Alignment - spaces at right side will be used first

Simply change to %-8.2f to have left alignment

If the number of spaces for fractional part is not specified, (example : %8f), default (6) would be used.

If the spaces specified are not enough (example: %3f), default setting would be used.

R M 3 8 8 . 8 9

Standard I/O Functions – printf()What’s the output

printf(“%-3s%7.3f\n”,” RM”, 388.88888);

R M 3 8 8 . 8 8 9

printf(“%-.2f\n”, 388.88888);

3 8 8 . 8 9

printf(“%4.2f\n”, 388.88888);

3 8 8 . 8 9

Standard I/O Functions – printf()

Can the field width be specified by a variable? YES!

Consider this example

for (i = 0; i < 4; i++)

printf(“%.*f\n”, i, 3.123456);

Output

3

3 . 1

3 . 1 2

3 . 1 2 3

The asterisk ‘*’ is a variable width determined by variable i

Standard I/O Functions – printf()

What’s output

for (i = 1; i < 4; i++)

printf(“%-*d%*d\n”, i, i, i, i);

Output

1 1

2 2

3 3

Standard I/O Functions – printf()

Develop an interactive program that can be used to teach multiplication to grade school students. The program should prompt the user to enter two three-digit integers, verify that they are indeed three-digit integers, and then print the product of the integers according to the following format

435

x 148

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8 times 435 is 3480

4 times 435 is 1740

1 times 435 is 435

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Add the products to get 64380