Question

How to replace lowercase characters by uppercase & uppercase characters by lowercase in C

Answer 1

#include <stdio.h> 
#include <string.h> 
#include <ctype.h> 
 
int main(void)
{   
    char s[100] = "C c++ Java JavaScript c# PHP";
    int len = strlen(s);
    
    for (int i = 0; i < len; i++)
        s[i] = islower(s[i]) ? toupper(s[i]) : tolower(s[i]);

    printf("%s\n", s);
     
    return 0;
}
 
         
/*
run:
      
c C++ jAVA jAVAsCRIPT C# php
 
*/

 

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