What does "%3d" mean in a printf statement?

Question

In this code what is the role of the symbol "%3d"? I know that % means refer to a variable.

This is the code:

#include <stdio.h>
int main(void)
{
    int t, i, num[3][4];
    for(t=0; t<3; ++t)
        for(i=0; i<4; ++i)
            num[t][i] = (t*4)+i+1;
    /* now print them out */
    for(t=0; t<3; ++t) {
        for(i=0; i<4; ++i)
            printf("%3d ", num[t][i]);
        printf("\n");
    }
    return 0;
}

Answer 1

That is a format specifier to print a decimal number (d) in three (at least) digits (3).

From man printf:

An optional decimal digit string specifying a minimum field width. If the converted value has fewer characters than the field width, it will be padded with spaces on the left (or right, if the left-adjustment flag has been given) to fill out the field width.

Answer 2

It is a formatting specification. %3d says: print the argument as a decimal, of width 3 digits.

Answer 3

Literally, it means to print an integer padded to three digits with spaces. The % introduces a format specifier, the 3 indicates 3 digits, and the d indicates an integer. Thus, the value of num[t][i] is printed to the screen as a value such as " 1", " 2", " 12", etc.

Answer 4

%3d can be broken down as follows:

• % means "Print a variable here"
• 3 means "use at least 3 spaces to display, padding as needed"
• d means "The variable will be an integer"

Putting these together, it means "Print an integer, taking minimum 3 spaces"

See http://www.cplusplus.com/reference/clibrary/cstdio/printf/ for more information

Answer 5

Thanks Guys For Your Answer !