资源描述:
《Objective-C 2.0 2数据类型和表达式.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、数据类型和表达式青岛滨海学院计算机教研室崔守良数据类型和常量数据类型的作用常量和变量的定义1、int类型如果整数值的第一位是0,表示用8进制计数,格式符为%o如果以0x开头,表示16进制计数,格式符为%x2、float类型和double类型%f,%e或%g3、char类型单引号引起来的单个字符@“binhai”字符串常量练习intmain(intargc,constchar*argv[]){@autoreleasepool{intintegerVar=100;floatfloatVar=123.45;doubledoubleVar=8.88e+1
2、2;charcharVar='b';NSLog(@"integerVar=%i",integerVar);NSLog(@"floatVar=%f",floatVar);NSLog(@"doubleVar=%e",doubleVar);NSLog(@"doubleVar=%g",doubleVar);NSLog(@"charVar=%c",charVar);}return0;}4、限定词long,longlong,short,unsigned和signedlongintnumberOfPoints=12345678900L;NSLog(@”numb
3、erOfPointsis%li”,numberOfPoints);unsignedintcounter=18000U;NSLog(@”unsignedintnumberis%u",counter);5、id类型Id类型可存储任何类型的对象。从某种意义上说,它是一般对象类型表达式1、算术表达式2、模运算符intmain(intargc,constchar*argv[]){@autoreleasepool{inta=25,b=5,c=10,d=7;NSLog(@"a%%b=%i",a%b);NSLog(@"a%%c=%i",a%c);NSLog(@"
4、a%%d=%i",a%d);NSLog(@"a/d*d+a%%d=%i",a/d*d+a%d);}return0;}3、整型值和浮点值的相互转换intmain(intargc,constchar*argv[]){@autoreleasepool{floatf1=123.123,f2;inti1,i2=-150;i1=f1;NSLog(@"%fassignedtoanintproduce%i",f1,i1);f1=i2;NSLog(@"%iassignedtoanfloatproduce%f",i2,f1);f1=i2/100;NSLog(@"%i
5、dividedby100produce%f",i2,f1);f2=i2/100.0;NSLog(@"%idividedby100.0produce%f",i2,f2);f2=(float)i2/100;NSLog(@"(float)%idividedby100produce%f",i2,f2);}return0;}练习定义一个计算器类Calculator,它是一个简单的四则计算器,可用来执行加、减、乘和除运算。因此,方法必须能够执行以下操作:将累加器设置为特定值、将其清空或设置为0,以及在完成时检索它的值。计算器类的定义#import6、ation/Foundation.h>@interfaceCalculator:NSObject{doubleaccumulator;}-(void)setAccumulator:(double)value;-(void)clear;-(double)accumulator;-(void)print;-(void)add:(double)value;-(void)subtract:(double)value;-(void)multiply:(double)value;-(void)divide:(double)value;@end计算器类的实现#
7、import"Calculator.h"@implementationCalculator-(void)setAccumulator:(double)value{accumulator=value;}-(void)clear{accumulator=0;}-(double)accumulator{returnaccumulator;}-(void)print{NSLog(@"Theresultis%g",accumulator);}-(void)add:(double)value{accumulator+=value;}-(void)subtra
8、ct:(double)value{accumulator-=value;}-(void)multiply:(double)value{a