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Trouble using strstr after fgets

Discussion in 'C' started by p3tr0va, Jun 7, 2014.

  1. p3tr0va

    p3tr0va New Member

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    Hi everybody.
    I want to use fgets to read a line of text and a word. The text is examined to find the word, but the word is never found even when the word is in the text.
    What am I doing wrong?
    Thanks.

    Code:
    #define TEXT_LEN 100
    #define WORD_LEN 20
    
      char text[TEXT_LEN];
      char word[WORD_LEN];
     
      printf("Enter the text to be searched:\n");
      fgets(text, TEXT_LEN, stdin);
    
      printf("Enter the word sought:\n");
      fgets(word, WORD_LEN, stdin);
    
      if(strstr(text, word))
        puts("The word sought was found");
      else
        puts("The word sought was not found");
     
  2. p3tr0va

    p3tr0va New Member

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    The problem is the character '\n' at the final of the word. fgets reads the new line character. Use gets(word) instead of fgets(word, WORD_LEN, stdin).
     
  3. p3tr0va

    p3tr0va New Member

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    Thanks p3tr0va.
     
  4. p3tr0va

    p3tr0va New Member

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    You're welcome.
     
  5. hobbyist

    hobbyist New Member

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    Urm... no. gets will betray you as it offers no boundary check. There's nothing preventing a user from trying to stuff 100,000 characters into your 20 character array, and trash memory elsewhere.

    Code:
    char text[TEXT_LEN] = { 0 },
           *p;
    
    fgets(text, sizeof text, stdin);
    
    if((p = strchr(text, '\n')) != NULL)
        *p = 0;
    else
        while(getchar() != '\n') {}
    
     
  6. Elizabeth_Keen

    Elizabeth_Keen Banned

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    It's because fgets stores the newline character so when strstr does a comparison it fails.
    From the main page:
    fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A '\0' is stored after the last character in the buffer.

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