I don't think the answer given in c13 exercise 5 b is correct about c-solutions

[magict4]

I also feel the answer is wrong. Here is my proposing solution.

#include <ctype.h>
void capitalize(char *str) {
    char *c = str;
    while (*c != '\0') {
        if (isalpha(*c))
            *c = toupper(*c);
        c++;
    }
}

[BigWillem]

I virtually have the same answer, only without the if statement. I'm not sure, but I think toupper() only does something to characters in the alphabet so the isalpha() call would be redundant.

// using pointer arithemtic 
void capitalize2(char *str)
{
    char *p = str; 
    while(*p != '\0')
    {
        *p =  toupper(*p);
        *p++;
    }
    *p = '\0'; 

    printf("%s", str); 
}