如今统治市场的主流编程语言,如c++,java,大都是面向对象类型的编程语言。
而众所周知,c语言是面向过程的编程语言,但是它拥有一个类似于类的结构,叫做结构体,主要的区别在于结构体无法定义函数。
因此,为了c语言的结构体近似模拟类,我们可以在结构体中定义函数指针。
下面这个例子,是最常用的计算学生分数平均数的c++类模版:
#include <cstdio>
#include <iostream>
#include <cstdlib>
#define LINE for (i = 0 ; i < 60 ; i++) {printf("-");}printf("
");
#define SPACE for (i = 0 ; i < 20 ; i++) printf(" ");
using namespace std;
class Student
{
public:
double stuAvg(double score[]);
int num;
char name[10];
double score[3];
double average;
};
double Student::stuAvg(double score[]){
double sum = 0.0;
double average = 0.0;
for (int i=0 ; i < 3 ; i++)
{
sum += score[i];
}
return average = sum/3;
}
int main(void){
Student stu1;
for (int i = 0 ; i < 3 ; i++)
{
scanf("%lf",&stu1.score[i]);
}
stu1.num = 1001;
memset(stu1.name,0,sizeof(stu1.name));
strcat(stu1.name,"Peter");
stu1.average = stu1.stuAvg(stu1.score);
//Output Part
printf("NUM");
SPACE;
printf("NAME");
SPACE;
printf("AVERAGE");
printf("
");
LINE;
printf("%d",stu1.num);
SPACE;
printf("%s",stu1.name);
SPACE;
printf("%.2lf",stu1.average);
printf("
");
LINE;
return 0;
}
接下来我们使用结构体模拟上例中类的作用:
#include <stdio.h>
#include <stdlib.h>
#define LINE for (i = 0 ; i < 60 ; i++) {printf("-");}printf("
");
#define SPACE for (i = 0 ; i < 20 ; i++) printf(" ");
struct Student{
double (*stuAvg)(double score[]);
int num;
char name[10];
double score[3];
double average;
};
double Calc_Avg(double score[]){
int i = 0;
double sum = 0.0;
double average = 0.0;
for (i=0 ; i < 3 ; i++)
{
sum += score[i];
}
return average = sum/3;
}
void main(void){
int i = 0;
struct Student stu1;
for (i = 0 ; i < 3 ; i++)
{
scanf("%lf",&stu1.score[i]);
}
stu1.num = 1001;
memset(stu1.name,0,sizeof(stu1.name));
strcat(stu1.name,"Peter");
stu1.stuAvg = Calc_Avg;
stu1.average = stu1.stuAvg(stu1.score);
//Ouuput Part
printf("NUM");
SPACE;
printf("NAME");
SPACE;
printf("AVERAGE");
printf("
");
LINE;
printf("%d",stu1.num);
SPACE;
printf("%s",stu1.name);
SPACE;
printf("%.2lf",stu1.average);
printf("
");
LINE;
return;
}