pointer

#include <stdio.h>
int add(int , int );
int prnch(int , int );
int mul(int , int);
int main(){
  int (*fptr[3])(int, int) = {add, mul, prnch};
  int x = 10;
  int y = 20;
  int z=0;
  int i;
  for(i=0;i<3;i++){
    z += (*fptr[i])(x, y);
  }
  printf("z: %d\n", z);
  return 0;
}
int add(int a, int b){
  return printf("sum: %d\n", a+b);
}
int mul(int a, int b){
  return printf("mul: %d\n", a*b);
}
int prnch(int m, int n){
  while(n--){
    putchar('-');
  }
  putchar('\n');
  while(m--){
    putchar('-');
  }
  putchar('\n');
  return m - n;
}


the output is:
sum: 30
mul: 200
--------------------
----------
z: 17

why Z is equal to 17?

about the pointer

after reviewing Fardad's lecture, i have a question about the address.

#include <stdio.h>
int main(){
  int a[3][5]={
                {10,20,30,40,50},
                {100,200,300,400,500},
                {1000,2000,3000,4000,5000}
              };
  printf("%u\n", a);
  printf("%u\n", a+1);
  printf("%u\n", a[0]);
  printf("%u\n", a[0]+1);
  printf("%d, %d\n", *(*(a+2) + 3), a[2][3]);
  return 0;
}

in my opinion, the first one "a" is the same as the third one "a[0]". so they have the same address.
but is it the second one "a+1" = "a[0]+1"????

the output is:
2030780
2030800
2030780
2030784
4000, 4000

i don't know why???

int2str

const char* Int2Str(int num) {
 static char string[50];
 int count=1;
 int temp=num;
 int i=0;
 while(num=num/10){
  count++;
 }
 while(count)
 {
  string[count-1]= 48+temp%10;
 temp=temp/10;
 count--;
 }
 return string;
}