Programming Tutorials

Formatting with printf in C

By: Siva in C Tutorials on 2008-08-06  

We could right justify our output using the format specifiers. The field-width specifier tells printf() how many columns on screen should be used while printing a value(as in %wd),here the value is right justified and is padded with blanks on the left. If we include the minus sign in format specifier (as in %-wd), this means left justification is desired and the value will be padded with blanks on the right. 

Eg:- main()
{
int a,b;
a=2134;
b=2756;
printf(“%5d /n”,a);
printf(“%-5d /n”,b);
}

The output for “a” would be as

        2     1     3    4 

The output for “b” would be as

2 7 5 6

For float data type the format is % t.nf where ‘t’ denotes the total width and ‘n’ the number of decimal spaces. For example 

main()
{
float x,y;
x= 3.141592;
y=14.4;
printf(“%6.3f \n”,x);
printf(“%-5.2f \n”,y);
} 
 

The output for ‘x’ would be as

  3 . 1 4 2

The output for ‘y’ would be as

1 4 . 4 0

Similarly, for formatting a string %ds is used. For example, %10s ,%25s etc. The string could also be formatted using a decimal value, as in %5.3s. Here it specifies how many characters are to be printed. 

Example:

main()
{
char text1[ ] = “Hello”;
char text2[ ] =  “World”;
printf(“% 10s \n,text1);
printf(“%5.3s \n,text2);
printf(“%-5.3s,text2);
} 

The output for text1 would be as

          H e l l o

The output for text2 would be as

    w o r

The output for text2 would be as

w o r

Special Control Characters

Control characters are invisible on the screen. They have special purposes usually to do with cursor movement. They are written into an ordinary string by typing a backslash haracter \ followed by some other character. These characters are listed below.