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POreading CSV in C when the table is broken
 

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  1. POreading CSV in C when the table is broken
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    <p>here is my C code to read CSV file:</p> <pre><code>#include &lt;stdio.h&gt; struct record {long a,b,c; }; int main(void) { const char filename[] = "b.csv"; FILE *file = fopen(filename, "r"); if ( file != NULL ) { char line [ 80 ]; struct record record [ 50 ]; size_t count, i = 0; while ( i &lt; sizeof record / sizeof *record ) { if ( fgets(line, sizeof line, file) == NULL ) { break; } if ( sscanf(line, "%ld,%ld,%ld", &amp;record[i].a,&amp;record[i].b,&amp;record[i].c) == 3 ) { ++i; } } fclose(file); for ( count = i, i = 0; i &lt; count; ++i ) { printf("record[%lu]: a = %ld b = %ld c = %ld\n", (long unsigned)i, record[i].a, record[i].b,record[i].c); } } else { perror(filename); } return 0; } </code></pre> <p>/* file.csv</p> <pre><code>301,36,15 302,88,75 </code></pre> <p><em>/ /</em> my output</p> <pre><code>record[0]: a = 301 b = 36 c = 15 record[1]: a = 302 b = 88 c = 75 </code></pre> <p>*/</p> <p>I have 2 issues with above code..</p> <p>1st issue is : /* file.csv</p> <pre><code> 301,,15 302,88, ,,,34 </code></pre> <p>The output should be</p> <pre><code>record[0]: a = 301 b = 0 c = 15 record[1]: a = 302 b = 88 c = 0 record[2]: a = 0 b = 0 c = 34 </code></pre> <p>and the 2nd issue is it should read file until “eof”. here I have taken 50 as a static line number value. what changes I should make ?</p> <p>see I have changed code at this way...</p> <pre><code> const char* getfield(char* line, int num) { const char* tok; for (tok = strtok(line, ","); tok &amp;&amp; *tok; tok = strtok(NULL, ",\n")) { if (!--num) return tok; } return NULL; } int main() { FILE* stream = fopen("b.csv", "r"); char line[1024]; char *pstr;int num; const char* value; while (fgets(line, 1024, stream)) { char* tmp = strdup(line); //printf("Field 3 would be %s\n", getfield(tmp, 3)); value=getfield(tmp, 3); num =strtol(value,&amp;pstr,10); printf("Field 3 would be %d\n", num); // NOTE strtok clobbers tmp free(tmp); } } </code></pre>
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USJatin Bodarya
    1. USJatin Bodarya
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
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      1. PTAnswer
    1. This table or related slice is empty.
    1. COconsider return value of sscanf means how many actual assigments are done and accordingly put into data member
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      1. POreading CSV in C when the table is broken
      1. USOmkant
    2. COYou can also read a line and apply strtok on comma and if value then put into data
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      1. POreading CSV in C when the table is broken
      1. USOmkant
    3. COwhat abt if returns NULL ?
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      1. POreading CSV in C when the table is broken
      1. USJatin Bodarya
 

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