C - reading multiple file streams - c

Question

Im writing my own simplified version of the classic UNIX program 'wc' (word count). It counts number of lines, words, and characters. All these features work fine. But where i run into trouble is when im trying to read multiple files from *argv[x]. I need to make every variable into an array, and run the whole process through loops to achieve what im looking for.
My program returns a segmentation fault. Something is not being assigned into the arrays at some point in the code, and i can't seem to figure out exactly where that is.
Any help is much appreciated :)
/*
* [PROGRAM] wc (word count)
* [AUTHOR] Jesper M. Olsen # jm0.codes
* [DATE] September 9th 2015
* [PURPOSE] Returns number of lines, words, and characters in a file
*
* [DESCRIPTION] This program is meant to be utilized as a handy little browsing tool.
* For instance, while moving through the filesystem of a programming archive,
* just type 'wc <filename>' and you will get number of lines, words and characters returned promptly.
*/
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
if (argc == 1)
return -1;
int numL[argc]; /* initialize array value placeholders */
int numW[argc];
int numC[argc];
int getC[argc];
int getW[argc];
int setNull;
for (setNull = 1; setNull <= argc-1; setNull++) { /* assign ZERO to value placeholders */
numL[setNull] = 0;
numW[setNull] = 0;
numC[setNull] = 0;
getW[setNull] = 0;
}
int x;
FILE *fOp[argc-1];
for (x = 1; x <= argc-1; x++) { /* open file stream for each file */
fOp[x] = fopen(argv[x], "r");
if (fOp[x] == NULL)
return -1;
}
int y;
for (y = 1; (getC[y] = getc(fOp[y])) != EOF; y++) {
if (getC[y] == '\n') numL[y]++;
if (getC[y] == ' ' || getC[y] == '\n' || getC[y] == '\t') getW[y] = 0;
else if (getW[y] == 0) {
getW[y] = 1;
numW[y]++;
} numC[y]++;
}
int z;
for (z = 1; z <= argc-1; z++) { /* close files */
fclose(fOp[z]);
}
int c;
for (c = 1; c <= argc-1; c++) {
printf("[%s] %dL %dW %dC\n", argv[c], numL[c], numW[c], numC[c]);
}
return 0;
}

Answer 1

This will cause a segfault when you reach the last file
FILE *fOp[argc-1];
for (x = 1; x <= argc-1; x++) { /* open file stream for each file */
fOp[x] = fopen(argv[x], "r");
if (fOp[x] == NULL)
return -1;
}
because the array is not large enough. It should be
FILE *fOp[argc];
The mistake would be easier to see if you used
< argc
instead of
<= argc-1
in your loops.

Answer 2

I think problem may be
here -
for (y = 1; (getC[y] = getc(fOp[y])) != EOF; y++) {
if (getC[y] == '\n') numL[y]++;
if (getC[y] == ' ' || getC[y] == '\n' || getC[y] == '\t') getW[y] = 0;
else if (getW[y] == 0) {
getW[y] = 1;
numW[y]++;
} numC[y]++;
}
As arrays can argc number of elements but with this loop you may have read and stored integers more than argc in getC . Thus getting Seg Fault .
But we don't know what it inside files we can't be sure.
Try increasing size of arrays .
Note - It is better to initialize array starting with index 0. In this code you haven't use index 0.