1、.初學(xué) C語言常用簡單程序代碼素?cái)?shù)的篩選#include <stdio.h>#include <math.h>#define N 1000int 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",numi);

2、return 0;輸出時(shí)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;printf("%d時(shí)%d分%d秒",d,t,s);三個(gè)數(shù)的交換#include <stdio.h>void main()int a,b,c,t;scanf("%d%d%d",&a,&b,&c);printf("The original number:a=%d,b=%d,c=%d

3、n",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 語句的運(yùn)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=3;break;case 6:m=2

4、;break;default:m=1;printf("m=%d",m);判斷奇數(shù)和偶數(shù)#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!");小寫改大寫，若是大寫則不變include <stdio.h>main()char c1,c

5、2;printf("Input a lettern");scanf("%c",&c1);c2=('a'<=c1&&c1<='z')?(c1-'a'+'A'):c1;printf("%c",c2);getchar();return 0;.輸入一個(gè)數(shù)，輸出這個(gè)數(shù)是幾位數(shù)#include <stdio.h>main()int x,n;printf("please input a number:");scanf(

6、"%d",&x);n=0;while(x!=0)x=x/10;n+;printf("%d",n);輸入一個(gè)數(shù)，判斷它是幾位數(shù)，然后逆序輸出#include<stdio.h>intmain()intnum;intlen=0;inttemp=0;printf("Pleaseinputanumber:n");scanf("%d",&num);while(num%10)!=0)temp=temp*10+(num%10);len+;.num=num/10;printf("length=%

7、dn",len);printf("Reverseis%d",temp);打印水仙花數(shù)#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");判斷閏年#include "stdio.h"main()int k,flag,n=0;for(k=1980;k<=2880;k+);

8、.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;sum=sum+t*i;printf("sum=%d",sum);求前 n 項(xiàng)和#include <

9、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);開發(fā)一個(gè)程序求全班學(xué)生某門課的平均成績， 要求程序每次運(yùn)行時(shí)班級人數(shù)可為任意/* 用標(biāo)記值來指示數(shù)據(jù)輸入的結(jié)束*/#include <stdio.h>main()float average,

10、total;int counter,score;total=0.0;counter=0;printf("輸入成績 ,-1 表示結(jié)束 :");scanf("%d",&score);while(score!=-1)/*用-1 表示輸入的結(jié)束 , 同時(shí)循環(huán)輸入分?jǐn)?shù) */;.total=total+score;counter+;printf("輸入下一個(gè)成績 ,-1 表示輸入結(jié)束 :");scanf("%d",&score);if(counter!=0)average=total/counter;print

11、f("全班平均成績?yōu)椋?%.2fn",average);elseprintf("沒有輸入成績 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)/(2.0*a);x2=(-b-delta)/(2.0*a);printf("x1=%f x2=%fn",x1,x2);.if語句的

12、運(yùn)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;elseif(c>0)w=a-b;elset=c;printf("s=%d, w=%d,t=%d",s,w,t);輸入學(xué)生的生日，輸出他的實(shí)足年齡#include <stdio.h>main()int y0,m0,d0,y1,m1,d1,age;.printf("nplease input birthday

13、(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>=d0)age=y1-y0;elseage=y1-y0-1;printf("age=%d n",age);指針變量作為函數(shù)

14、參數(shù)，實(shí)現(xiàn)兩數(shù)的交換#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)int t;t=*x;*x=*y;*y=t;通過函數(shù)調(diào)用輸出兩個(gè)實(shí)型數(shù)中最大的一個(gè)#include <stdio.h>float *f(float *

15、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);計(jì)算并輸出一個(gè)數(shù)組中所有元素的和，最大值，最小值，值為奇數(shù)的元素個(gè)數(shù)編寫一個(gè)函數(shù)，將一個(gè)字符串中的字符全部轉(zhuǎn)成大寫#include <stdio.h>void Lower2Upper(char *str)char *p=str;while(*p!=0)if(*p<='z

16、9;&&*p>='a')*p=*p-32;p+;main()char s10="Hello!".int i;Lower2Upper(s);for(i=0;i<10;i+)printf("%c",si);計(jì)算一個(gè)字符在一個(gè)字符串中出現(xiàn)的次數(shù)#include <stdio.h>int count(char ch,char *str)char *p=str;int num=0;while(*p!='0')if(*p+=ch)num+;return num;main()char ah=

17、9;a'char s="haowareayou"printf("the number is:");printf("%dn",count('a',s);刪除一維數(shù)組中所有相同的數(shù)#include <stdio.h>.void unique(int *a,int *n)int k=1;int i,m;m=a0;for(i=0;i<*n;i+)if(ai>m)ak+=ai;m=ai;*n=k;main()int a10;int n=10,i;printf("input a list

18、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 delete.n");for(i=0;i<n;i+)printf("%d",ai);printf("n");.將字符串按字典順序輸出#include <stdio.h>#i

19、nclude <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=namek;namek=pt;