初学C语言常用简单程序代码

1、初学C语言常用简单程序代码素数的筛选#include <stdio.h> #include <math.h> #define N 1000 int main(int argc, char* argv)int i,j,numN; for(i=0;i<N;i+) numi=i+1;for(i=1;i<(int)sqrt(double)N);i+) if(numi)for(j=i+1;j<N;j+) if(numj) if(numj%numi=0) numj=0; for(i=1;i<N;i+) if(numi) printf(" %d&qu

2、ot;,numi); return 0; 输出时分秒 #include <stdio.h> main()int x,s,t,d;scanf("%d",&x);s=x%60;t=(x/60)%60;d=(x/60)/60;prin tf("%d 时 小分 %d秒 ",d,t,s); 三个数的交换 #include <stdio.h> void main() int a,b,c,t;scanf("%d%d%d",&a,&b,&c);printf("The original

3、number:a=%d,b=%d,c=%dn",a,b,c);t=a,a=b,b=t;t=a,a=c,c=t;printf("after swap:a=%d,b=%d,c=%d",a,b,c);switch 语句的运用#include <stdio.h>main()int a,m;printf("please input a number:");scanf("%d",&a);switch(a/10)case 10:case 9: m=5; break;case 8: m=4; break;case 7:m

4、=3; break;case 6:m=2; break;default:m=1;printf("m=%d",m); 判断奇数和偶数 #include <stdio.h> main()int x;printf("Please input a number: ");scanf("%d",&x);if(x%2=0)printf("this is a oushu!");elseprintf("this is a jishu!"); 小写改大写，若是大写则不变 include <

5、stdio.h> main()char c1,c2;printf("Input a lettern");scanf("%c",&c1);c2=('a'<=c1&&c1<='z')?(c1-'a'+'A'):c1;printf("%c",c2);getchar();return 0; 输入一个数，输出这个数是几位数 #include <stdio.h>main()int x,n;printf("please i

6、nput a number:"); scanf("%d",&x);n=0;while(x!=0)x=x/10;n+;printf("%d",n);输入一个数，判断它是几位数，然后逆序输出 #include<stdio.h>int main()int num;int len = 0;int temp =0;printf("Please input a number:n"); scanf("%d",&num);while(num % 10)!=0)temp = temp*10+(n

7、um%10);len+;num = num/10;printf("length = %dn",len); printf("Reverse is %d", temp);打印水仙花数#include <stdio.h> main()int x, a,b,c;for(x=100;x<=999;x+)a=x%10; b=(x/10)%10;c=x/100; if(x=a*a*a+b*b*b+c*c*c) printf("%5d",x); printf("n");判断闰年#include "std

8、io.h" main()int k,flag,n=0; for(k=1980;k<=2880;k+) flag=(k%4=0)&&(k%100!=0)|(k%400=0);if(flag) printf("%5d",k);n+; if(n%10=0) printf("n");printf("n");求 1-3+5-7.-99+101 的值#include <stdio.h>main()int sum,i,t;sum=1;t=1; for(i=3;i<=101;i=i+2)t=-t; s

9、um=sum+t*i;printf("sum=%d",sum);求前 n 项和#include <stdio.h> main()float s,t;int n,i,fz,fm;s=0;fz=2;fm=1;printf("Enter n:"); scanf("%d",&n); for(i=1;i<=n;i+)t=(1.0*fz)/fm;s=s+t;fz=fz+fm; fm=fz-fm;printf("s=%fn",s);开发一个程序求全班学生某门课的平均成绩， 要求程序每次运行时班 级人数可

10、为任意/* 用标记值来指示数据输入的结束 */#include <stdio.h>main()float average,total;int counter,score;total=0.0;counter=0;printf(" 输入成绩 ,-1 表示结束 :");scanf("%d",&score);while(score!=-1) /*用-1 表示输入的结束 , 同时循环输入分数 */total=total+score; counter+;printf(" 输入下一个成绩 ,-1 表示输入结束 :"); scan

11、f("%d",&score);if(counter!=0)average=total/counter;printf(" 全班平均成绩为： %.2fn",average);elseprintf(" 没有输入成绩 n");return 0;求二元一次方程的根#include <stdio.h>#include <math.h>main()float a=4,b=-40,c=91;float x1,x2;float delta;delta=sqrt(b*b-4.0*a*c);x1=(-b+delta)/(2.

12、0*a);x2=(-b-delta)/(2.0*a);printf("x1=%f x2=%fn",x1,x2);if 语句的运用#include <stdio.h>main()int a,b,c,s,w,t;s=w=t=0;a=-1;b=c=3;if(c>0)s=a+b;if(a<=0)if(b>0)if(c<=0)w=a-b;else if(c>0) w=a-b;else t=c;printf("s=%d, w=%d,t=%d",s,w,t); 输入学生的生日，输出他的实足年龄 #include <std

13、io.h> main()int y0,m0,d0,y1,m1,d1,age;printf("nplease input birthday (yyyy/mm/dd):"); scanf("%d/%d/%d ",&y0,&m0,&d0);printf("nplease input current day(yyyy/mm/dd):"); scanf("%d/%d/%d ",&y1,&m1,&d1);if(m1>m0) | (m1=m0 && d1

14、>=d0) age=y1-y0;else age=y1-y0-1;printf("age=%d n",age); 指针变量作为函数参数，实现两数的交换 #include <stdio.h> void sswap(int *x,int *y);main()int a=10,b=20;printf("before swap:a=%d,b=%dn",a,b);sswap(&a,&b);printf("after swap:a=%d,b=%dn",a,b);void sswap(int *x,int *y)i

15、nt t;t=*x;*x=*y;*y=t;通过函数调用输出两个实型数中最大的一个#include <stdio.h>float *f(float *px,float *py)if(*px>*py)return px;return py;main()float x=10.0,y=20.0,*a=&x,*b=&y; printf("*a=%f,*b=%f,max=%fn",*a,*b,*f(a,b); 计算并输出一个数组中所有元素的和，最大值，最小值，值为奇数的 元素个数编写一个函数，将一个字符串中的字符全部转成大写#include <s

16、tdio.h>void Lower2Upper(char *str)char *p=str;while(*p!=0)if(*p<='z'&&*p>='a') *p=*p-32;p+;main()char s10="Hello!"int i;Lower2Upper(s);for(i=0;i<10;i+)printf("%c",si); 计算一个字符在一个字符串中出现的次数 #include <stdio.h>int count(char ch,char *str)char

17、*p=str;int num=0;while(*p!='0')if(*p+=ch)num+;return num;main()char ah='a'char s="haowareayou"printf("the number is:");printf("%dn",count('a',s); 删除一维数组中所有相同的数 #include <stdio.h> void unique(int *a,int *n)int k=1;int i,m; m=a0;for(i=0;i<

18、*n;i+)if(ai>m) ak+=ai; m=ai;*n=k;main()int a10;int n=10,i;printf("input a list number:"); for(i=0;i<n;i+) scanf("%d",&ai); printf("Before delete:.n"); for(i=0;i<n;i+) printf("%d",ai); unique(a,&n); printf("after deleten");for(i=0;i&l

19、t;n;i+)printf("%d",ai);printf("n"); 将字符串按字典顺序输出 #include <stdio.h> #include <string.h>#define N 5void sort(char *name,int n);void prn(char *name,int n);void main()char*name="China","America","Australia","France","German" sort(name,N);prn(name,N);void sort(char *name,int n)char *pt;int i,j,k;for(i=0;i<n-1;i+)k=i;for(j=i+1;j<n;j+)if(strcmp(namek,namej)>0)k=j;if(k!=i)pt=namei;namei=na