Question

How to convert a string characters: upper to lower and lower to upper in C

Answer 1

#include <stdio.h>
#include <ctype.h> 

int main(int argc, char **argv) 
{ 
    char s[] = "Convert a HARD DISK or partition TO NTFS format";
    int i = 0;
        
    while (s[i])
    {
        if (islower(s[i]))
            s[i] = toupper(s[i]);
        else if (isupper(s[i]))
                 s[i] = tolower(s[i]);
        i++;
    }
 
    printf("%s\n", s);
    
    return(0);
}


/*
run:

cONVERT A hard disk OR PARTITION to ntfs FORMAT

*/

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