c function to lowercase a string code example
Example: convert string to lowercase in c
// include all the libraries used in the program.
#include <stdio.h>
#include <cs50.h>
#include <ctype.h>
#include <string.h>
#include <math.h>
// Base Function
int main(int argc, string argv[])
{
if (argc != 2)
{
printf("Usage: ./substitution key\n");
}
else if (strlen(argv[1]) != 26)
{
printf("Key must contain 26 characters.\n");
}
string key = argv[1].toupper();
string key = argv[1].tolower();
}