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    <p>Here is some code that will do what you are asking. I think it will help you understand how string functions work a little better. Note - I did not make many assumptions about how well conditioned the input and text file are, so there is a fair bit of code for removing whitespace from the input, and for checking that the match is truly "the first word", and not "the first part of the first word". So this code will not match the input "hello" to the line "helloworld 123 234" but it will match to "hello world 123 234". Note also that it is currently case sensitive.</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;string.h&gt; int main(void) { char buf[100]; // declare space for the input string FILE *fp; // pointer to the text file char fileBuf[256]; // space to keep a line from the file int ii, ll; printf("give a word to check:\n"); fgets(buf, 100, stdin); // fgets prevents you reading in a string longer than buffer printf("you entered: %s\n", buf); // check we read correctly // see (for debug) if there are any odd characters: printf("In hex, that is "); ll = strlen(buf); for(ii = 0; ii &lt; ll; ii++) printf("%2X ", buf[ii]); printf("\n"); // probably see a carriage return - depends on OS. Get rid of it! // note I could have used the result that ii is strlen(but) but // that makes the code harder to understand for(ii = strlen(buf) - 1; ii &gt;=0; ii--) { if (isspace(buf[ii])) buf[ii]='\0'; } // open the file: if((fp=fopen("myFile.txt", "r"))==NULL) { printf("cannot open file!\n"); return 0; } while( fgets(fileBuf, 256, fp) ) { // read in one line at a time until eof printf("line read: %s", fileBuf); // show we read it correctly // find whitespace: we need to keep only the first word. ii = 0; while(!isspace(fileBuf[ii]) &amp;&amp; ii &lt; 255) ii++; // now compare input string with first word from input file: if (strlen(buf)==ii &amp;&amp; strstr(fileBuf, buf) == fileBuf) { printf("found a matching line: %s\n", fileBuf); break; } } // when you get here, fileBuf will contain the line you are interested in // the second and third word of the line are what you are really after. } </code></pre>
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    1. POHow would I compare a string (entered by the user) to the first word of a line in a file?
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    1. USFloris
    1. USFloris
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    1. POHow would I compare a string (entered by the user) to the first word of a line in a file?
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    1. VO
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      1. VTUpMod
    2. VO
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      1. VTAcceptedByOriginator
    1. COWhy use `strstr()` when `strcmp()` or `strncmp()` could be used instead, and they won't search through the whole string — they'll only search for a match at the start of the string.
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      1. USJonathan Leffler
    2. CO1) fgets() stores the '\n' at the end of the string into the buffer, too. 2) `for(ii = 0; ii < strlen(buf); ii++)` is a terrible idiom, resulting in quadratic behaviour. 3) `while(!feof(fp)) {` is anothe bad idiom. 4) `while(!isspace(fileBuf[ii]) && ii < 255)` the manifest constant `255` is a disaster waiting to happen. sizeof is your friend
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      1. USwildplasser
    3. CO@wildplasser - regarding point 1: I was trying to show that a newline was generated. But I'm not sure if it's always just a single character, or can be two (CRLF). Regarding point 2: I wasn't trying to be most efficient; just showing that an extra character existed at the end of the string (which makes a beginner wonder why the strings won't match). I wouldn't use it in "real" code. I will update.
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      1. USFloris
 

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