String search C program for command prompt - c

Question

I wrote C program of searching string. The problem is MyStrstr() function doesn't work with
command prompt. It only works with IDE. So, can anyone advise me how to fix the code for working with command prompt. With regards...
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define ARGUMENT_COUNT 3
#define FILE_INDEX 2
#define SEARCH_INDEX 1
#define BUFFER 256
#define SUCCESS 0
#define ERRCODE_PARAM 1
#define ERRCODE_FILENAME 2
#define MSG_USAGE "String Search Program === EXER5 === by Newbie\nUsage: %s Search_String fileName"
#define MSG_ERROR "Can not open file. [%s]"
char* MyStrstr(char* pszSearchString, char* pszSearchWord);
int main(int argc, char* argv[])
{
FILE* pFile = NULL;
char szData[BUFFER];
char* pszCutString = NULL;
if(argc != ARGUMENT_COUNT) {
printf(MSG_USAGE, argv[0]);
return ERRCODE_PARAM;
}
pFile = fopen(argv[FILE_INDEX], "r");
if(pFile == NULL) {
printf(MSG_ERROR, argv[FILE_INDEX]);
return ERRCODE_FILENAME;
}
pszCutString = MyStrstr(szData, argv[SEARCH_INDEX]);
if(pszCutString != NULL) {
printf("%s", pszCutString);
}
fclose(pFile);
pFile = NULL;
return SUCCESS;
}
char* MyStrstr(char* pszSearchString, char* pszSearchWord) {
int nFcount = 0;
int nScount = 0;
int nSearchLen = 0;
int nIndex = 0;
char* pszDelString = NULL;
char cSLen = 0;
size_t len = 0;
if(pszSearchString == NULL || pszSearchWord == NULL) {
return NULL;
}
while(pszSearchWord[nSearchLen] != '\0') {
nSearchLen++;
}
if(nSearchLen <= 0){
return pszSearchString;
}
cSLen = *pszSearchWord++;
if (!cSLen) {
return (char*) pszSearchString;
}
len = strlen(pszSearchWord);
do {
char cMLength;
do {
cMLength = *pszSearchString++;
if (!cMLength)
return (char *) 0;
} while (cMLength != cSLen);
} while (strncmp(pszSearchString, pszSearchWord, len) != 0);
return (char *) (pszSearchString - 1);
}

Answer 1

You want to open a file, search the contents of that file for a string and return/print that. You are instead doing:
char szData[256]; // <-- making an uninitialized buffer
char* pszCutString = NULL;
pFile = fopen(argv[2], "r"); // <-- Opening a file
pszCutString = MyStrstr(szData, argv[1]); // <-- searching the buffer
if(pszCutString != NULL) {
printf("%s", pszCutString);
}
fclose(pFile); // <-- Closing the file
So you never fill your buffer szData with the contents of the file noted in argv[2]. You're trying to search an uninitialized buffer for a string. You're luck the result is just "no output comes out".
You need to take the contents of the file in argv[2] and place it in the buffer szData then do the search. This could be accomplished by adding a call to a function like read() or fscanf()
Note 1:
I assume when you say this "worked" in the IDE, the code was a little different and you weren't using the command line arguments.
Note 2:
you should also check to fopen() worked before trying to read from/close pFile, and if your file is possibly larger than 256 characters you will need to change your code to either have a dynamically sized string, or you'll need to loop the buffer fills (but then you have to worry about breaking a word apart), or some other mechanism to check the full file.