To Lower

#include "stdio.h" 
char lwr(char v)

{
     if(v>='A' && v<='Z')
     return ('a'+v-'A');
     else
     return (v);
}
int main (void)
{
    char ch;
    printf("Enter a Uppercase letter:\n");
    scanf("%c", &ch);
    printf("The uppercase form of %c is %c\n", ch, lwr(ch));
    system("pause");
    return 0;
}