paste

The paste Command

paste merges corresponding lines from two inputs side-by-side with a delimiter:

$ paste -d: names.txt ages.txt
alice:30
bob:25
carol:35

Line 1 of names.txt is joined to line 1 of ages.txt with :, and so on.

Your Implementation

Write void my_paste(const char *a, const char *b, char delim) that merges lines from a and b with delim.

The algorithm: advance through both strings simultaneously. For each pair of lines, print the line from a, then the delimiter, then the line from b, then a newline.

void my_paste(const char *a, const char *b, char delim) {
    while (*a || *b) {
        while (*a && *a != '\n') { putchar(*a); a++; }
        putchar(delim);
        while (*b && *b != '\n') { putchar(*b); b++; }
        putchar('\n');
        if (*a == '\n') a++;
        if (*b == '\n') b++;
    }
}

Two Pointers, One Loop

Unlike previous tools that operate on a single string, paste walks two strings at once. The while (*a || *b) condition continues as long as either string still has content — so if one is longer, its extra lines still appear (with an empty other side).

Your Task

Implement my_paste that merges lines from a and b with the given delimiter.