C プログラム: テキスト内の単語を別の指定された単語に置き換えます

text = “I am learning programming”
oldword = “learning”
newword = “practicing”

“I am practicing programming”

#include 
#include 
#include 
void replaceWordInText(const char *text, const char *oldWord, const char *newWord) {
   int i = 0, cnt = 0;
   int len1 = strlen(newWord);
   int len2 = strlen(oldWord);
   for (i = 0; text[i] != '\0'; i++) {
      if (strstr(&text[i], oldWord) == &text[i]) {
         cnt++;
         i += len2 - 1;
      }
   }
   char *newString = (char *)malloc(i + cnt * (len1 - len2) + 1);
   i = 0;
   while (*text) {
      if (strstr(text, oldWord) == text) {
         strcpy(&newString[i], newWord);
         i += len1;
         text += len2;
      }
      else
      newString[i++] = *text++;
   }
   printf("New String: %s
", newString);
}
int main() {
   char str[] = "I am learning programming";
   char c[] = "learning";
   char d[] = "practicing";
   char *result = NULL;
   printf("Original string: %s
", str);
   replaceWordInText(str, c, d);
   return 0;
}

Original string: I am learning programming
New String: I am practicing programming