[C 언어] 함수 주소 전달 & 주소 리턴

 

<예제 1>

#include <stdio.h>
int f(int *i, int j);

int main(void){
  int x=10, y=20;
  printf("%d\n", f(&x, y)); 
  printf("%d %d", x, y);
}

int f(int *i, int j){
  *i += 5;
  return (2* *i + ++j);
  }
// 51
// 15 20

 

<예제 2>

#include <stdio.h>

int foo(int a, int *b);

int main(){
  int a=5;
  int b=3;
  int c=0;
  b = foo(a, &c);
  c = foo(b, &c);
  printf("a=%d b=%d c=%d", a, b, c);
}

int foo(int a, int *b){
  int c;
  *b = a+1;
  c = a-1;
  return c;
}
// a=5 b=4 c=3

 

<예제 3>

#include <stdio.h>

void swap(int a, int *b);

int main(){
  int value=3, list[4]={1,3,5,7};
  int i;
  swap(value, &list[0]);
  swap(list[2], &list[3]);
  swap(value, &list[value]);
  for(i=0; i < 4; i++) 
    printf("%d",list[i]);
}

void swap(int a, int *b){
  int temp;
  temp = a;
  a = *b;
  *b = temp;
}
//3353

 

 

<예제 4>

#include <stdio.h>

void change(int *px, int *py, int pc, int pd);

int main(void) {
  int a=10, b=20, c=30, d=40;
  change(&a, &b, c, d);
  printf("a=%d, b=%d, c=%d, d=%d", a, b, c, d);
}

void change(int *px, int *py, int pc, int pd){
  *px = *py + pd;
  *py = pc + pd;
  pc = *px + pd;
  pd = *px + *py;
}
// a=60, b=70, c=30, d=40

 

 

<예제 5>

#include <stdio.h>

double h(double *f, int d, double x);

int main(void) {
  double f[] = {1, 2, 3, 4};
  printf("%3.1f", h(f, 4, 2));
  return 0;
}

double h(double *f, int d, double x){
  int i;
  double res = 0.0;
  for(i=d-1; i>=0; i--){
    res = res * x + f[i];
  }
  return res;
}
// 49.0

 

<예제 6>

#include <stdio.h>
void func(int *a, int b, int *c);

int main() {
  int a, b, c[1];
  a=20;
  b=20;
  c[0] = 20;
  func(&a, b, c);
  printf("d=%d, b=%d, c=%d", a, b, c[0]);
  return 0;
}

void func(int *a, int b, int *c){
  int x;
  x = *a;
  *a = x++;
  x = b;
  b = ++x;
  --(*c);
}
// a=20, b=20, c=19

 

<예제 7>

#include <stdio.h>
#define SIZE 3

void func(int *m, int *x, int y);

int main() {
  int num[SIZE] = {1, 3, 6};
  int a=10, b=30;
  func(num, &a, b);
  printf("a=%d, b=%d", a, b);
  return 0;
}

void func(int *m, int *x, int y){
  int i=0, n=0;
  y = *x;
  n = *(m+1) + (*m+2);
  *x = ++n;
}
// a=7, b=30

<예제 8>

#include <stdio.h>
int *func(int a, int *x);

int main() {
  int i;
  int x=10;
  int *p;
  int a[100];
  for(i=0; i<100; i++)
    a[i] = i*10;
  p = func(x, a);
  printf("sum=%d", x + a[0] + a[1] + p[0] + p[1]);
}

int *func(int a, int *x){
  a = a + 10;
  x = x + 1;
  *x = *x * 2;
  return x;
}
// sum=70

 

 

 

 

 

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