ios入门calculator类的编写

      初学IOS对编程的逻辑进行的训练，通过编写一个简单的计算机程序来锻炼编程需要的罗辑思维。

Calc.h

//  Calc.h
//  practice_calc
//
//  Created by 李旗 on 15/11/2.
//  Copyright (c) 2015年 李旗. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Calc : NSObject
- (void) setAccumulator: (double) value;      

- (void) clear;
- (double) accumulator;

- (void) add :(double) value;
- (void) subtract :(double) value;
- (void) multiply :(double) value;
- (void) divide : (double) value;

//set calculator的 存储值 清除 加减乘除

@end

Calc.m

//
//  Calc.m
//  practice_calc
//
//  Created by 李旗 on 15/11/2.
//  Copyright (c) 2015年 李旗. All rights reserved.
//

#import "Calc.h"

@implementation Calc
{
    double accumulator;
}

-(void) setAccumulator:(double)value
{
    accumulator = value;                                           //为accumulator赋值
}

-(void) clear
{
    accumulator = 0;                                                //初始化accumulator
}

-(double) accumulator
{
    return accumulator;                                            //返回accumulator 
}

-(void) add:(double)value
{
    accumulator += value;
}

-(void) subtract:(double)value
{
    accumulator -= value;
}

-(void) multiply:(double)value
{
    accumulator *= value;
}

-(void) divide:(double)value
{
    accumulator /= value;
}

                                                                                       //加减乘除运算
@end

Main.m

//
//  main.m
//  practice_calc
//
//  Created by 李旗 on 15/11/2.
//  Copyright (c) 2015年 李旗. All rights reserved.
//

#import <Foundation/Foundation.h>
//#import"Calc.h"

int main(int argc, const char * argv[]) {
    @autoreleasepool
    {
        // insert code here...

           Calc *deskCalc =[[Calc alloc ] init ];         //声明一个deskCalc并且初始化
       
           [deskCalc setAccumulator: 100.0];
           [deskCalc add: 200.0];
           [deskCalc divide: 15.0];
           [deskCalc subtract: 10.0];
           [deskCalc multiply: 5];
                                                                             //进行运算
           NSLog(@"The result is %g",[deskCalc accumulator]);   //输出结果