Why strcmp doesn't work?

Question

The program works well. It verifies if an argument is a file or a directory and it returns 1 or 2. However, strcmp doesn't work and I don't know why.

Here is my code:

#DEFINE N 100
int main(int argc,char* argv[]) {

FILE *fp;
char cmd[N];
char result[N];
int i;

for(i=1;i<argc;i++){
    pipe(c2p);
    if (fork()==0){
        //Running the shell script
            sprintf(cmd,"/home/flory/os/verif.sh %s", argv[i]);
            fp = popen(cmd, "r");
            fgets(result, N, fp);
            pclose(fp);
            printf("%s",result);    
            if (strcmp(result,"1")==0){
                     //DO SOMETHING
            }
}

Answer 1

The variable x does not have a value yet.

Did you mean the following?

if (strcmp(result,"1")==0){
                 //DO SOMETHING
}

Answer 2

Apart from variable confusion in your question, please notice what happens with the trailing newline when reading a line of text. From linux man page fgets(3):

   fgets() reads in at most one less than size characters from stream  and
   stores  them  into  the buffer pointed to by s.  Reading stops after an
   EOF or a newline.  If a newline is read, it is stored into the  buffer.
   A '\0' is stored after the last character in the buffer.

I wrote a small program somewhat like yours:

#include <stdio.h>

main()
{
  FILE      *fp;
  char bigbuf[10*1024];

  fp = popen("/bin/echo hello world", "r");
  fgets(bigbuf, sizeof bigbuf, fp);

  printf("length of bigbuf: %d\nlength of \"hello world\": %d\n", strlen(bigbuf), strlen("hello world"));
  exit(0);
}

Running it, I get the following output:

length of bigbuf: 12
length of "hello world": 11

Answer 3

result has a terminating newline character since it has been read by fgets() , therefore, it would contain "1\\n" (or possibly "1\\r\\n" , though that's unlikely), which is different from "1" .

You can delete the newline like this:

char *p;
if((p=strchr(result,'\n'))!=0) *p=0;

If your input contains CR you can remove them the same way.