STL sort example (c++) with class, struct

#include <stdio.h>

#include <iostream>

#include <algorithm>

#include <functional>

using namespace std;

class t_A{

public:

int a;

int b;

};

#define MAX 30

t_A g_AA[3][MAX];

bool comp_A(const t_A& a, const t_A& b) {

return a.b < b.b;

}

void test_A_sort()

{

t_A* g_A = g_AA[0];

//init

for (int i = 0; i < MAX; i++) {

g_A[i].a = i;

g_A[i].b = i%7;

}

sort(g_A, g_A + MAX, comp_A);

for (int i = 0; i < MAX; i++) {

printf("%d %d\n", g_A[i].a, g_A[i].b);

}

}

////////////////////////

int g_N[MAX];

int* g_pN[MAX];

bool cmp_pN(int*a, int* b) {

return *a < *b;

}

void pointer_test() {

printf("== pointer_test ==\n");

for (int i = 0; i < MAX; i++) {

g_N[i] = i%7;

g_pN[i] = &(g_N[i]);

}

for (int i = 0; i < MAX; i++) {

printf("%d, ", *(g_pN[i]));

}

printf("\n");

sort(g_pN, g_pN + MAX, cmp_pN);

for (int i = 0; i < MAX; i++) {

printf("%d, ", *(g_pN[i]));

}

printf("\n");

}

////////////////////////

int g_NN[3][MAX];

int* g_pNN[3][MAX];

bool cmp_pNN(int*a, int* b) {

return *a < *b;

}

void pointer_test_2() {

printf("== pointer_test_2 ==\n");

for (int j = 0; j < 3; j++) {

for (int i = 0; i < MAX; i++) {

g_NN[j][i] = i % 9 + j;

g_pNN[j][i] = &(g_NN[j][i]);

}

}

for (int i = 0; i < MAX; i++) {

printf("%d, ", *(g_pNN[0][i]));

}

printf("\n");

sort(g_pNN[0], g_pNN[0] + MAX, cmp_pNN);

for (int i = 0; i < MAX; i++) {

printf("%d, ", *(g_pNN[0][i]));

}

printf("\n");

}

////////////////////////

class t_AAA {

public:

int a;

int b;

};

t_AAA g_AAA[3][MAX];

t_AAA* g_pAAA[3][MAX];

bool cmp_pAAA(t_AAA* l, t_AAA* r) {

return l->b < r->b;

}

void pointer_test_3() {

printf("== pointer_test_3 ==\n");

for (int j = 0; j < 3; j++) {

for (int i = 0; i < MAX; i++) {

g_AAA[j][i].a = i;

g_AAA[j][i].b = i % 9 + j;

g_pAAA[j][i] = &(g_AAA[j][i]);

}

}

for (int i = 0; i < MAX; i++) {

printf("(%2d, %2d), ", (g_pAAA[0][i]->a), (g_pAAA[0][i]->b));

}

printf("\n");

sort(g_pAAA[0], g_pAAA[0] + MAX, cmp_pAAA);

for (int i = 0; i < MAX; i++) {

printf("(%2d, %2d), ", (g_pAAA[0][i]->a), (g_pAAA[0][i]->b));

}

printf("\n");

}

////////////////////////

bool cmp(int a, int b) { return a<b; }

int main()

{

int a[] = { 6, 1, 3, 2, 4 };

sort(a, a + 5, greater<int>());

sort(a, a + 5, less<int>());

sort(a, a + 5, cmp);

for (int i = 0; i < (sizeof(a) / sizeof(int)); i++) printf("%d, ", a[i]);

printf("\n");

//test_A_sort();

//pointer_test();

pointer_test_3();

return 0;

}