#include <stdio.h>
#include <string.h>
#include <ctype.h>
void convert_part_to_uppercase(char s[], int idx_from, int idx_to) {
if (idx_from < 0 || idx_to > strlen(s)) return;
for (int i = 0; i < strlen(s); i++) {
if ((i >= idx_from && i <= idx_to) && (s[i] >= 'a' && s[i] <= 'z')) {
s[i] = toupper(s[i]);
}
}
}
int main()
{
char s[] = "c programming";
convert_part_to_uppercase(s, 3, 5);
puts(s);
convert_part_to_uppercase(s, 8, 9);
puts(s);
return 0;
}
/*
run:
c pROGramming
c pROGraMMing
*/