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    #include <stdio.h>

    void functionlower(char []);

    int main()
    {
       char string[100];

       printf("Enter a string to convert it into lower case\n");
       gets(string);

       functionlower(string); // calling functionlower

       printf("Entered string in lower case is %s", string);

       return 0;
    }

    void functionlower(char s[]) {
       int c = 0;

       while (s[c] != '\0') {
          if (s[c] >= 'A' && s[c] <= 'Z') {
             s[c] = s[c] + 32;
          }
          c++;
       }
    }