编写程序，实现以下函数功能，并使用C++函数重载功能使以下函数支持各种基本数据类型： 1. 比较两数大小 2. 求平方 3. 求绝对值 4. 求三角形的面积

很高兴回答你的问题！以下是实现以上函数功能的C代码，已使用函数重载功能实现支持各种基本数据类型：

#include <stdio.h>
#include <math.h>

float compare(float a, float b) {
    if(a > b) {
        return a;
    } else {
        return b;
    }
}

int compare(int a, int b) {
    if(a > b) {
        return a;
    } else {
        return b;
    }
}

float square(float n) {
    return pow(n, 2);
}

int square(int n) {
    return pow(n, 2);
}

float absolute(float n) {
    return fabs(n);
}

int absolute(int n) {
    return abs(n);
}

float triangleArea(float base, float height) {
    return (base * height) / 2;
}

int triangleArea(int base, int height) {
    return (base * height) / 2;
}

int main() {
    float f1 = 1.5;
    float f2 = 2.7;
    printf("The bigger number is: %f\n", compare(f1, f2));

    int i1 = 3;
    int i2 = 6;
    printf("The bigger number is: %d\n", compare(i1, i2));

    float n1 = 5.0;
    int n2 = 7;
    printf("The square of the first number is: %f\n", square(n1));
    printf("The square of the second number is: %d\n", square(n2));

    float n3 = -3.5;
    int n4 = -2;
    printf("The absolute value of the first number is: %f\n", absolute(n3));
    printf("The absolute value of the second number is: %d\n", absolute(n4));

    float base = 4.0;
    float height = 5.0;
    printf("The area of the triangle is: %f\n", triangleArea(base, height));

    int base2 = 6;
    int height2 = 8;
    printf("The area of the triangle is: %d\n", triangleArea(base2, height2));

    return 0;
}