The third day of Camp David

Although many code teachers have already written a calculator, they still encounter many problems. Although some syntax is still unclear, they generally ask students and teachers. the running process has already been used to understand the logic of the Code.

#import <UIKit/UIKit.h>@interface ViewController : UIViewController@property (weak, nonatomic) IBOutlet UILabel *wang;@end

 

#import "ViewController.h"@interface ViewController (){    NSString *op1,*op2;    char op ;}@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    op1 = @"";    op2 = @"";    // Do any additional setup after loading the view, typically from a nib.}- (IBAction)touch1:(id)sender {    NSLog(@"1 touch");    if(op!=‘+‘&&op!=‘-‘&&op!=‘*‘&&op!=‘/‘){        op1 = [NSString stringWithFormat:@"%@%d",op1,1];    }    else{        op2 = [NSString stringWithFormat:@"%@%d",op2, 1];    }        }- (IBAction)touch2:(id)sender {    NSLog(@"2 touch");    if(op!=‘+‘&&op!=‘-‘&&op!=‘*‘&&op!=‘/‘){        op1 = [NSString stringWithFormat:@"%@%d",op1,2];    }    else{        op2 = [NSString stringWithFormat:@"%@%d",op2,2];    }    }- (IBAction)touch3:(id)sender {    NSLog(@"3 touch");    if(op!=‘+‘&&op!=‘-‘&&op!=‘*‘&&op!=‘/‘){        op1 = [NSString stringWithFormat:@"%@%d",op1,3];    }    else{        op2 = [NSString stringWithFormat:@"%@%d",op2,3];    }}- (IBAction)touch4:(id)sender {    NSLog(@"4 touch");    if(op!=‘+‘&&op!=‘-‘&&op!=‘*‘&&op!=‘/‘){        op1 = [NSString stringWithFormat:@"%@%d",op1,4];    }    else{        op2 = [NSString stringWithFormat:@"%@%d",op2,4];    }}- (IBAction)add:(id)sender {    op = ‘+‘;}- (IBAction)jian:(id)sender {    op =‘-‘;}- (IBAction)cheng:(id)sender {    op=‘*‘;}- (IBAction)chu:(id)sender {    op=‘/‘;}- (IBAction)equl:(id)sender { if (op == ‘+‘) {    int a1 = [op1 intValue];    int a2 = [op2 intValue];    int sum = a1 + a2;    NSLog(@"%d", sum);    NSString *result = [NSString stringWithFormat:@"%d", sum];     self.wang.text = result;     }}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end

 

The third day of Camp David