学习笔记（90):C语言入门到精通-命令行参数

立即学习:https://edu.csdn/course/play/10534/380032?utm_source=blogtoedu

#include <stdio.h>
#include <stdlib.h>

// 计算器，实现+,-,*,/
int main(int argc, char *arg[]) {
	double a = 0.0; 
	double b = 0.0;
	char op = '\0';
	double ret = 0.0;

	if (argc != 4) {
		printf("参数错误, argc = %d, %s\n", argc, arg[0]);
		return -1;
	}

	a = atof(arg[1]);
	op = arg[2][0];
	b = atof(arg[3]);

	switch (op) {
	case '+': ret = a + b; break;
	case '-': ret = a - b; break;
	case '*': ret = a * b; break;
	case '/': ret = a / b; break;
	default: printf("运算符错误\n"); return -1;
	}

	//if (op == '+') {
	//	ret = a + b;
	//}
	//else if (op == '-') {
	//	ret = a - b;
	//}
	//else if (op == '*') {
	//	ret = a * b;
	//}
	//else if (op == '/') {
	//	ret = a / b;
	//}
	//else {
	//	printf("运算符错误\n");
	//	return -1;
	//}

	printf("%lf %c %lf = %lf\n", a, op, b, ret);
	return 0;
}