Pattern Matching in C

#include 
#include 
#include 

void sgrep(char *filename, char *pattern);

int main(int argc, char *argv[])
{
char *filename;
FILE *file;
char *pattern;
int hit;
if(argc<2)
{
printf("missing argument\n");
}
else
{
if(argc==2)
{
filename = argv[1];
printf("Pattern to search for:\n");
scanf("%s",pattern);
sgrep(filename,pattern);
//printf("MAIN: hit=%d\n",hit);

}
}

return 0;
}
void sgrep(char *filename, char *pattern)
{
//Search file for the first character in the pattern
int i;
FILE *file;
char *chars = "1";
char *filedata;
char first;
int index;
int j;
int k;
int hit;
if((file=fopen(filename,"r"))==NULL)
{
printf("cannot open file %s\n",filename);
}
else
{
file=fopen(filename,"r");
char *data = (char*)malloc(100);
while(chars)
{
chars = fgets(data,100,file);

if(chars)
{
for(i=0;i