循环程序实现要点
- 哪些操作需要反复执行——循环体
- 在什么情况下执行——循环控制条件
三种循环语句
- for语句（实现给定了循环次数）
- while
- do while（先经循环体运算一次）
例4-8-1
#include<stdio.h>
int main()
{
int i,mark,max,n;
printf("Enter n:" );
scanf("%d",&n);
printf("Enter %d marks",n);
scanf("%d" , &mark);
max=mark;
for(i=1; i<n; i++){
scanf("%d",&mark);
if(max<mark)
max=mark;
}
printf("Max=% d\n",max);
return 0;
}
Enter n:5
Enter 5 marks67 88 73 54 82
Max= 88
例4-8-2
#include<stdio.h>
int main()
{
int mark,max;
printf("Enter marks: ");
scanf("% d",&mark);
max=mark;
while(mark>=0){
if(max<mark)
max=mark;
scanf("%d",&mark);
};
printf("Max=%d\n",max);
return 0;
}
Enter marks: 67 88 73 54 82 -1
Max=88
例4-9
#include<stdio.h>
int main()
{
int x;
printf("Enter x:");
scanf("%d",&x);
while(x !=0){
printf("%d",x%10);
x=x/10;
}
return 0;
}
Enter x:12345
54321
例4-10
#include<stdio.h>
#include<math.h>
int main()
{
int count,i,m,n;
count=0;
for(m=2; m<=100;m++){
n=sqrt(m);
for(i=2; i<=n; i++)
if(m%i==0) //如果m是素数
break;
if(i>n){
printf("%6d",m);
count++;
if(count%10==0)
printf("\n");
}
}
printf("\n");
return 0;
}
2 3 5 7 11 13 17 19 23 29
31 37 41 43 47 53 59 61 67 71
73 79 83 89 97
例4-11
#include<stdio.h>
int main()
{
int i,x1,x2,x;
x1=1;
x2=1;
printf("%6d%6d",x1,x2);
for(i=1; i<=8; i++){
x=x1+x2;
printf("%6d",x);
x1=x2;
x2=x;
}
printf("\n");
return 0;
}
1 1 2 3 5 8 13 21 34 55
例4-12
#include<stdio.h>
int main()
{
int child,men,women;
for(men=0; men<=45; men++)
for(women=0;women<=45;women++)
for(child=0;child<=45;child++)
if(men+women+child==45&&men*3+women*2+child*0.5==45)
printf("men=%d,women=%d,child=%d\n",men,women,child);
return 0;
}
men=0,women=15,child=30
men=3,women=10,child=32
men=6,women=5,child=34
men=9,women=0,child=36
或者是
#include<stdio.h>
int main()
{
int child,men,women;
for(men=0; men<=15; men++)
for(women=0;women<=22;women++){
child=45-women-men;
for(child=0;child<=45;child++)
if(men+women+child==45&&men*3+women*2+child*0.5==45)
printf("men=%d,women=%d,child=%d\n",men,women,child);
}
return 0;
}
men=0,women=15,child=30
men=3,women=10,child=32
men=6,women=5,child=34
men=9,women=0,child=36