strrchr help

Hi guys

I'm having trouble with the code below.
I know strchr and strrchr both take int's as the second argument but I don't know how to make it work the way I want.
With strrchr I manually pass '/' as the second argument and it works.

I've tried different int's & chars using typecasting but I can't make it work by passing a variable. I don't know why it takes an int when likely we are going to be searching for some chars?

Here is the current code and error I get.

Thanks so much for your help guys!

Quote:

---

lastoccurrence.c: In function `main':
lastoccurrence.c:29: warning: passing arg 2 of `strchr' makes integer from pointer without a cast

---

Code:

---

int main(int argc, char *argv[])
{
char stringsearch[900];
char *stringtosearch[900];
char *result;
/*printf("Argc=%d\n",argc);*/

  if( argc != 2 )
  {
      printf("WTF: You need to enter 1 arguments: The string to search in\n");
      return 39798;
  }

strcpy(stringsearch,argv[1]);

/*
printf("String To Search=%s\n",stringtosearch);
printf("ARG1 (string to search)=%s\n",stringsearch);
*/

result=strrchr(stringsearch,'/');
result=strchr(stringsearch,result);
printf("%s\n",result);
return 0;
}

---

Code:

---

char *result;

...

result=strchr(stringsearch,result);

---

If you know strchr() takes an int as a second parameter, why are you trying to stuff a char * down its throat? Square Peg, meet Round Hole. lol....

I know, that is my point and example. :)
I know it can't work but there must be a way to accomplish what I want.

I don't understand why I can pass it '/' manually and it works....because a slash is not an int.
I want to somehow be able to pass a char variable instead as the second parameter.

Is something like this possible?

Otherwise I don't understand the point of the function if I can't make it dynamic by passing some sort of variable to it.

Does anyone have a solution?

A '/' can indeed be an int.

Take a short time-out, and consider the difference between char and int and char *. The following information is based upon a 32-bit, x86 system. The numbers below are not to be considered valid for actual calculations that require 100% correct information.

With that said......

A char is a one byte variable. An int is a four byte variable. A char * is a four byte variable designed to hold the address of a char (which is only one byte). Human readable characters, mainly the English set, are able to be stored into a byte. This includes your '/' char. By convention, the '/' has a numerical representation of 47 (check an ASCII table). Such a number can be held in either a char or an int.

This is why you can pass '/' to strchr() because you're just giving it a value of 47. Hence, it assumes you're sending it as an int, since it makes the most sense. ;) It wants an int, and it knows a char can fit inside of an int, so it implicitly does the typecasting.

A char *, however, is not quite related. It's a pointer to a char, although it's generally used to mean to be a pointer to a contiguous sequence of chars.

'/' is not a string. It's not a char *. It's a simple char that can be viewed as an int. :)

Umm . . . like this?

Code:

---

char c = '/';
const char *string = "/usr/bin/program";
char *p = strrchr(string, c);

---

You can't use a char*, you need to use a char.

If you want to search for the next '/' in a string, add the previous position to the beginning of the string, plus one:

Code:

---

char dirsep = '/';
const char *program = "/usr/bin/program";
char *one = strchr(program, c);

if(program[one-program]) {
    char *two = strchr(program + one-program + 1, c);
}

---

The if statement prevents the +1 running off the end of the string if the string was, say, "/usr/".

Thanks guys for your help and wisdom.
I think I need to re-evaluate how I want to accomplish what I want to accomplish.

I guess basically what I'm trying to do is:
Take the result of "result=strrchr(stringsearch,'/');"
And then remove that portion from the rest of the original string.

I'll think about it and come back and post either way :)

Thanks again.

You guys are all geniuses, good at explaining things and friendly....I couldn't ask for a better community

result in this case will just be a pointer to the location where the char was found. If such a char was found, then take everything before it, and everything after it and make it a new concatenated string.

If you need to keep the buffer, then you could just shift everything after the char in question over one.