Interleave 2 strings together

c/interleave.c

@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+char *interleave(char *str1, size_t len1, char *str2, size_t len2) {
+  char *combined = malloc(len1 + len2 + 1);
+
+  if(!combined) {
+    return NULL;
+  }
+
+  char *idx = combined;
+
+  while(*str1 && *str2) {
+    *idx = *str1, *(idx + 1) = *str2;
+    idx += 2, str1 += 1, str2 += 1;
+  }
+
+  char *rest = str1;
+
+  if(*str2) {
+    rest = str2;
+  }
+
+  strcat(idx, rest);
+  return combined;
+}
+
+int main(int argc, char **argv) {
+  if(argc != 3) {
+    return 1;
+  }
+
+  size_t len1 = strlen(argv[1]);
+  size_t len2 = strlen(argv[2]);
+
+  char *combined = interleave(argv[1], len1, argv[2], len2);
+
+  if(!combined) {
+    return 1;
+  }
+
+  printf("%s\n", combined);
+  free(combined);
+  return 0;
+}