Centering strings with printf()

Question

By default, printf() seems to align strings to the right.

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printf("%10s %20s %20s\n", "col1", "col2", "col3"); /*       col1                 col2                 col3 */ 

I can also align text to the left like this:

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printf("%-10s %-20s %-20s", "col1", "col2", "col3"); 

Is there a quick way to center text? Or do I have to write a function that turns a string like test into (space)(space)test(space)(space) if the text width for that column is 8?

Answer 1

printf by itself can't do the trick, but you could play with the "indirect" width, which specifies the width by reading it from an argument. Lets' try this (ok, not perfect)

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void f(char *s) {         printf("---%*s%*s---\n",10+strlen(s)/2,s,10-strlen(s)/2,""); } int main(int argc, char **argv) {         f("uno");         f("quattro");         return 0; } 

Answer 2

@GiuseppeGuerrini's was helpful, by suggesting how to use print format specifiers and dividing the whitespace. Unfortunately, it can truncate text.

The following solves the problem of truncation (assuming the field specified is actually large enough to hold the text).

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void centerText(char *text, int fieldWidth) {     int padlen = (fieldWidth - strlen(text)) / 2;     printf("%*s%s%*s\n", padLen, "", text, padlen, ""); }