2、x
3、<10X<10
4、
5、x>10//
6、x
7、>10变目运算++--操作一个整型变量X++;++x;<=>x=x+1;X--;--x;三目运算？：Y=12?3:6;Y=a?B:c//若a!=0,则y=b若a==0，则y=c#includeMain(){inta,
8、b,x;Printf("inputa,b=");Scanf("%d%d",&a,&b);X=(a>b)?a:b//取a，b中大的那个数Printf("x=%d",x);}循环语句While（表达式）语句；I=1//初始化While(i<=10){....;....I++;//，每次变化}S=1+2+3+.....+100S=1-2+3-4+....#include#includeMain()Main(){ints,i;{inti,s,t;I=1;s=0;Printf("inputn=");While(i<=100)Scanf("%d"
9、,&n);{s=s+i;I=1;s=0;t=1;I++;While(i<=n)}{s=s+t*i;Printf("s=%d",s);t=-t;}i++;}Printf("s=%d",s);}S=1+1/2+1/3+1/4+...1/100Pi/4=1-1/3+1/5-1/7-1/9+...#include#includeMain()#include{inti;Main()Floats;{inti；I=1;s=0;Floats,t,k;While(i<=100)I=1;s=0;t=4;k=t;{s=s+1.0/n;W
10、hile(fabs(k)>1e-6)I++;//1e-6=10-6fabs求绝对值函数}{s=s+k;Printf("s=%f",s);t=-t;}i=i+2;K=t/i;}Printf("pi=%f",s);}判断用户输入一个数十素数#include#includeMain(){inti,n,k;Printf("inputn=");Scanf("%d",&n);I=2;k=0;While(i<=sqrt(n))//sqrt(n)=把n开方{if(n%i==0){k=i;//做标志Break;}I++;}If(k)printf("n
11、o!,%d",k);elsePrintf("yes");}字符型{chara;//字符型A='A';A='4';//Ascll完全等价：a=48;A=4;}{A='T'+2;//T=84Printf("a=%d",a);}//a=86{chara;A='T'+2;Printf("a=%c",a);//%c是输出字符}//a=V类型转换{intx;X=34;y=367.22;X=(int)y;//x=367取整Y=(float)x;X=(int)(k+0.5);//四舍五入X=((int)(10*k+0.5))/10.0//在十分之一四舍五入多重分支p68Intx
12、,y;Scanf("%d",&x);Switch(表达式)//整型表达式，产生整数{case值1：语句1；//值是整型常量case值2：语句2；case值3：语句3；........Default:语句n;}多重循环#include#includeMain(){intx,y;for语句X=1;{intx,y;While(x<=10)for(x=1;x<=10;x++){y=1;{for(y=1;y<=x;y++)printf("#");While(y<=10)printf("");{printf("#");}Y++;}Printf("
13、n");X++;}}9*9乘法表从100到1000找到a3+b3+c3=abc#include#includeMain()main(){intx,y;{inta,b,c,x;For(x=1;x<10;x++)for(x=100;x<1000;x++)For(y=1;y<=x;y++){a=x/100;{printf("%d*%d=%d",y,x,x*y);b=x%100/10;If(x*y<10)printf("")c=x%10;}if(a*a*a+b*b*b+c*c*c==x)
