1、(3)2.89e+12L(4)”String+” FOO”(5)x, *, *, 2(6)”X?/”(7)a, ?, b(8)x, -, +=, y(9)intx, =, +, 10(10)”String”, “FOO”2.3不是表识符的如下:4th 首字母为数字 sizeof关键字x*y *不是字母、数字、下划线temp-2 -不是字母、数字、下划线isnt 不是字母、数字、下划线enum 关键字2.4合法常数:.12 0.L 1.E-5 3.F 浮点型常量2L 33333 0377UL 0x9cfU 整型常量“a” “” 字符串常量45 0 a 字符常量非法常数:必须用转义序列0x1ag
2、十六进制没有gE20 没有尾数部分18 要用八进制数0xa 格式错误,可以是xa“34” 需要转义序列”2.5(1)int a, b=5;(2)double h;(3)int x=2.3; 0.3 会被截取。(4)const long y=1; 必须赋初值(5)float a= 2.5*g; g 没有定义。(6) int a=b=2; 在 turbo C 中编译出错:未定义的符号b在main函数中。2.6(1)4(2)0(3)1(4)6(5)8(6)0(7)3.00(8)1(9)108(10)02.7 答案不确定(1)a=b=c c未定义(2)正确(3)正确(4)正确(5)a*+-b 表达式缺
3、值(6)a|bi 运算的操作数必须是整型,而i不是(7)i*j%a %运算的操作数必须是整型,而a不是(8)正确(9)正确(10)int(a+b) 应该改成(int)(a+b)2.9(1)0(2)-2(3)65535(4)5(5)60(6)113(7)-2(8)-1(9)65532(10)32.10unsigned long encrypt(unsigned long x) unsigned long x0,x1,x2,x3,x4,x5,x6,x7; x0=(x & 0x0000000F) 8; x1=(x & 0x000000F0); x2=(x & 0x00000F00) x3=(x &
4、0x0000F000); x4=(x & 0x000F0000) 24; x7=(x & 0xF0000000); return(x0|x1|x2|x3|x4|x5|x6|x7);2.11#includevoid main()unsigned long in;unsigned long a,b,c,d;scanf(%ld,&in);/in=1563;a=(in&0xff000000)24;b=(in&0x00ff0000)16;c=(in&0x0000ff00)8;d=in&0x000000ff;printf(%d.%d.%d.%d,a,b,c,d);2.15(k 8)& 0xFF00) |
5、(p & 0x00FF)b?ac?a:c:bb:c;max=a b ? (a c) ? a : c):(b b : c);2.17X=yn2.18(c=0 & c=0cAFaf) printf(%dn,c-); else if(c+10); else putchar(c);3.9 short num,high,low;Please input a short number:n scanf(%hdnum); low = 0x00ff & num; high = 0x00ff & (num 8);The high byte is:%cn, high);The low byte is:, low);
6、 3.10#include stdafx.hint main(int argc, char* argv) unsigned short int x; unsigned short int high,low;input a integer:%dx); high = (x12)&0x000f; low = (x(m-n+1)(15-n+1);%hun,result);3.12 float f,c;%ff); c=(5*(f-32)/9;%.0f(F)=%.2f(C)n,f,c);或者int f;float c;%d(F)=%.2f(C)n3.13#include #define PI (3.141
7、5926) double r, h; double s, v;Please input the r and h.%lf,%lf, &r, &h); s = 2 * PI * r * h + 2 * PI * r * r; v = PI * r * r * h;s is %lf, v is %lf, s, v);3.14 char a4 = 编;机内码:%x%xtn,a0&0xff,a1&0xff);区位码:%xtn0xff8+a1&0xff-0x2020-0x8080);国际码:0xff-0x8080);第四章习题4.1void main(void)float a,b,c;Please ent
8、er the score of A:a);Please enter the score of B:b);Please enter the score of C:c);if(a-b)*(a-c)0)A gets the score %.1f,a);if(b-a)*(b-c)B gets the score %.1f,b);if(c-a)*(c-b)1)days+=mdays(y,m-1);m-;,days);4.4 if方法: float x = 0;input the salaryn if(x0 & x1000)0n else if(x=EPS) pi=pi+t; n=n+2; s=s*(-1); t=s/n; pi=pi*4;pi=%10.6fn,pi);4.11int main() int a,b,num1,num2,temp;Input a & b:%d%dnum1,&num2); if(num1num2) temp=num1; num1=num2; num2=
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