Format formatting specifier in printf

Question

I have several lines of output, for example:

    printf("%-20s %-20s %-20s %-20s %-20s \n", "Identity", "Identity", "float", "double", "long double");
    printf("%-20s %-20s %-20s %-20s %-20s \n", "Number", "LHS", "error", "error", "error");

As you can see, if I wanted to change the interval between them, I would have to change the number 20 ten times. Is there a way to parameterize a format specifier? So that changing only once will change them all?

Answer 1

Yes, you can make the field width an asterisk ( *) and specify the value as an argument int. Sort of

printf("%-*s \n", width, "Identity");

where widthhas a type intcontaining the value of the field width. You can change the value widthto change the width of the field.

C11 , §7.21.6.1, fprintf(),

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