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习题11.1 书写一个简单的C++程序，从而理解C++程序的结构及特点。该程序只由一个主函数组成，主函数的函数体中只包含一个语句：coutThis is a C++ program.;【1.1答】#include iostream.hvoid main(){cout This is a C++ program.;}?习题22.1????? 写出C++标识符的命名规则，写出5个合法的标识符和5个不合法的标识符。2.2????? 下列符号哪些是C++标识符？哪些不是，为什么？2m? a+c? int? i*j? mm? data? n-a? m22? x? -n? a_1【2.2答】mm? data? m22? x? a_1 是C++标识符，int是是C++标识符也是关键字2.3????? 指出下列合法的常量，并说明其类型。???? 65538?? 1.3?? 2.1E4 7L? 9uL? 9? a? 123u【2.3答】65538?? 整型常量1.3???? double型常量2.1E4?? double型常量7L???? 长整型常量9uL???? 无符号长整型常量9???? 字符型常量a???? 字符型常量123u??? 无符号整型常量2.4????? 写出符合C++规则的int、double、char和字符串4种类型的常量各2个。2.5????? 说明字符常量和字符串常量有何区别？2.6????? 下列变量的定义是否合法？为什么？⑴ INT? i,j,k;??? ⑵? char c1,c2;??? ⑶ int a,b;float f,b;⑷ unsigned int m? ⑸? char: a1,a2,a3; ⑹ unsigned float x,y;【2.6答】⑵和⑶合法。⑴的INT要小写；⑷少分号；⑸char后多了冒号；⑹数据类型错误2.7????? 将下列数学表示式写成C++表达式。（1）??????????? （2）(3)????????????? (4)????【2.7答】（1）(2*x*x+3*y*y)/(x-y)（2）(-b+sqrt(b*b-4*a*c))/(2*a)??? 和? (-b-sqrt(b*b-4*a*c))/(2*a)或 (-b+sqrt(b*b-4*a*c))/2/a?????? 和? (-b-sqrt(b*b-4*a*c))/2/a（3）1+(1+a/b)/(1-(a/c)（4）x/sqrt(fabs(x*x*x+y*y*y+z*z*z))2.8????? 已有如下变量定义，求下列表达式的值。⑴double x=1.2,y=8.5;int a=3;x+a%3*(int)(x+y)⑵int a=2,b=3;double x=3.5,y=2.5;(double)(a+b)/2+(int)x%(int)y⑶int x=4,y=8;(++x)*(--y)⑷int e=1,f=4,g=2;double m=10.5,n=4.0,k;k=(e+f)/g+sqrt(n)*1.2/g+m⑸double x=2.5,y=4.7;int a=7;x+a%3*(int)(x+y)%2/4⑹int a,b;int x;x=(a=2,b=5,a++,b++,a+b)【2.8答】⑴? 1.2⑵ 3.5⑶ 35⑷ 13.7⑸ 2.5⑹? 9⑴? 1.2#include iostream.hvoid main(){??? double x=1.2,y=8.5;??? int a=3;??? cout(x+a%3*(int)(x+y))endl;}⑵ 3.5#include iostream.hvoid main(){??? int a=2,b=3;??? double x=3.5,y=2.5;??? cout((double)(a+b)/2+(int)x%(int)y)endl;}⑶ 35#include iostream.hvoid main(){??? int x=4,y=8;??? cout((++x)*(--y))endl;}⑷? 13.7#include iostream.h#include math.hvoid main(){??? int e=1,f=4,g=2;??? double m=10.5,n=4.0,k;??? k=(e+f)/g+sqrt(n)*1.2/g+m;??? coutkendl;}⑸ 2.5#include iostream.hvoid main(){??? double x=2.5,y=4.7;??? int a=7;??? cout(x+a%3*(int)(x+y)%2/4)endl;}⑹? 9#include iostream.hvoid main(){??? int a,b;??