C: finding the number of elements in an array[]

Question

In C: How do you find the number of elements in an array of structs, after sending it to a function?

int main(void) {
  myStruct array[] = { struct1, struct2         


        

Answer 1

You may use a format for your array. I am using string elements, it should work for struct.

#define NULL ""
#define SAME 0

static char *check[] = {
      "des", "md5", "des3_ede", "rot13", "sha1", "sha224", "sha256",
      "blowfish", "twofish", "serpent", "sha384", "sha512", "md4", "aes",
      "cast6", "arc4", "michael_mic", "deflate", "crc32c", "tea", "xtea",
      "khazad", "wp512", "wp384", "wp256", "tnepres", "xeta",  "fcrypt",
      "camellia", "seed", "salsa20", "rmd128", "rmd160", "rmd256", "rmd320",
      "lzo", "cts", "zlib", NULL
 }; // 38 items, excluding NULL

in main ( )

char **algo = check;
int numberOfAlgo = 0;


while (SAME != strcmp(algo[numberOfAlgo], NULL)) {
    printf("Algo: %s \n", algo[numberOfAlgo++]);
}

printf("There are %d algos in the check list. \n", numberOfAlgo);

You should get the output:

Algo: des 
   :
   :
Algo: zlib 

There are 38 algos in the check list.

Alternatively, if you do not want to use the NULL , do this instead:

numberOfAlgo = 0;

while (*algo) {
    printf("Algo: %s \n", *algo);
    algo++;         // go to the next item
    numberOfAlgo++; // count the item
}

printf("There are %d algos in the check list. \n", numberOfAlgo);