Question

I am searching a string and the string could contain a newline or a CRLF. I increment the pointer to search through each character. I have converted the hex to decimal. However, as I am looking for a single char, I am not sure this would be the best way to do this.

Many thanks for any suggestions,

   /*
      0x0a (ASCII newline)
      0x0d (ASCII carriage return)
      CRLF (0x0d0a)
    */

    while(*search != '\0') {
        /* Seach for a newline */
        if(*search == 10) {
            printf("\nnewline Found\n");
        }

        /* Search for a CRLF */
        if(*search == 3338) {
            printf("\nCRLF Found\n");
        }

        search++;
    }

I’m compiling with gcc 4.6.2 in C89-mode.

Answer 1

CRLF is two characters: CR, and LF. You need to match them both individually, not together as you’ve done with 3338 (I think: where did you get that number?) Also, use the character constants: '\0', '\n', '\r', it will make your code clearer.

/*
  0x0a (ASCII newline)
  0x0d (ASCII carriage return)
  CRLF (0x0d0a)
*/

while(*search != '\0') {
    /* Seach for a newline */
    if(*search == '\n') {
        printf("\nnewline Found\n");
        search++;
    }

    /* Search for a CR or a CRLF */
    if(*search == '\r') {
        // OK, we found a CR, is it followed by a LF?
        if(*(search + 1) == '\n') {
            // Yes, it is, thus, it is a CRLF
            printf("\nCRLF Found\n");
            search += 2; // Note the 2! CRLF is 2 characters!
        }
        else {
            // No, just a lonely CR, forever alone.
            printf("\nCarriage return found\n");
            search++;
        }
    }
}

As another poster suggests, you can also use the strchr and strstr functions, and take the minimum valid result from them. (It’ll be like 3 lines of code.)