1 /* 2  计算器类 3  1>返回π 4  2>计算两个整数的平方 5  3>计算两个整数的和 6  */ 7  8  9 #import <Foundation/Foundation.h>10 11 @interface Calculator: NSObject12 //方法名:pi13 - (double) pi;14 15 //OC方法中，一个参数对应一个冒号:16 //方法名：squr:17 - (int) squr:(int) num;18 19 //方法名: sumWithNum1:andNum2:20 - (int) sumWithNum1:(int)num1 andNum2:(int)num2;21 22 @end23 24 25 @implementation Calculator26 - (double) pi27 {28     return 3.14;29 }30 31 - (int) squr: (int) num32 {33     return num * num;34 }35 36 - (int) sumWithNum1:(int)num1 andNum2:(int)num2;37 {38     return num1 + num2;39 }40 @end41 42 43 int main()44 {45     Calculator *c = [Calculator new];46     int d1 = 4;47     int d2 = 5;48     int d3 = 9;49     NSLog(@"PI = %f", [c pi]);50     NSLog(@"%d 的平方是 %d",d1, [c squr: d1]);51     NSLog(@"%d + %d = %d", d2, d3, [c sumWithNum1:d1 andNum2:d3]);52     return 0;53 }