strstr to find a word in a string using c returning true all the time

Question

Good Day,

So I decided to go trough my C again and started making a simple search the word in a string.

Here is my code:

#include<stdio.h>
#include<conio.h>
#include<string.h>

main(){
char word[100];
char sentence[100];

clrscr();
printf("Enter a word: ");
fgets(word, 100, stdin);
getch();
printf("The word is : %s", &word);
getch();
printf("\nEnter a sentence: ");
fgets(sentence, 100, stdin);
getch();
printf("The sentence is: %s",&sentence);
getch();
if(strstr(sentence,word) == 0){
  printf("word found!");
}
getch();
return 0;
}

The problem now is that whenever i try to search for the word in a string using strstr, it always returns word found. I also tried using strcmp but that will only compare the first instance of the string and stops when a match is not found so its not really advisable if you want to do a word searching in a string problem.

I haven't really made a program like this before, never needed one actually. So may I ask why is not working properly since according to its description strstr should be to search for a word in a sentence or did I just misunderstood it.

Also if you have any comments on my program feel free to say so, so that I may become aware of my mistake.

Thank you

Example: word: dog
sentence: the dog is here
should return true

Answer 1

This line

if(strstr(sentence,word) == 0)

should be

if(strstr(sentence,word) != NULL)

strstr() returns a pointer to the first occurence of word in sentence or NULL if the word was not found.

For details please read here.

---

Also using fgets() to read in the "strings" appends a '\n' to the end of the "strings". This prohibits successful comparsion.

To chop of the trailing '\n' you could do like this:

fgets(word, sizeof(word), stdin);
{
  size_t size = strlen(word);

  if (size && ('\n' == word[size-1]))
  {
    word[size-1] = '\0';
  }
}

Answer 2

Returns a pointer to the first occurrence of str2 in str1, or a null pointer if str2 is not part of str1.

Returning NULL (0) essentially means that the string was NOT found.

Thus

if(strstr(sentence,word) == 0){
  printf("word found!");
}

Should be

if(strstr(sentence,word) != NULL){
  printf("word found!");
}

Source - http://en.cppreference.com/w/c/string/byte/strstr

Additionally as Armin points out, you shouldn't use the address operator, &, in your printf. %s expects to have a pointer passed to printf and using the name of the array as sentence is actually the same as a pointer to the start of the array, i.e sentence == &sentence[0]