tr

The tr Command

tr (translate) maps every character in from to the corresponding character in to:

$ echo "hello" | tr 'aeiou' 'AEIOU'
hEllO
$ echo "hello world" | tr 'a-z' 'A-Z'
HELLO WORLD

Each character in from[i] is replaced by to[i]. Characters not in from pass through unchanged.

Your Implementation

Write void my_tr(const char *s, const char *from, const char *to) that translates characters.

For each character in s, search for it in from. If found at position i, print to[i]. Otherwise print the character as-is.

void my_tr(const char *s, const char *from, const char *to) {
    while (*s) {
        char c = *s;
        for (int i = 0; from[i] && to[i]; i++) {
            if (c == from[i]) { c = to[i]; break; }
        }
        putchar(c);
        s++;
    }
}

Why a Loop Instead of a Ternary?

The single-char version used *s == from ? to : *s. With a string mapping you need to search the full from table for a match. The inner for loop does this — it walks both from and to together, stopping when it finds a match or reaches the end.

Your Task

Implement my_tr that translates every character in s according to the from → to mapping.