初学C语言常用简单程序代码

1/3初学C语言常用简单程序代码素数的筛选#include<stdio.h>#include<math.h>#defineN1000intmain(intargc,char*argv[]){inti,j,num[N];for(i=0;i<N;i++)num[i]=i+1;for(i=1;i<(int)sqrt((double)N);i++){if(num[i]){for(j=i+1;j<N;j++){if(num[j])if(num[j]%num[i]==0)num[j]=0;}}}for(i=1;i<N;i++)if(num[i])printf("%d",num[i]);return0;}输出时分秒#include<stdio.h>main(){ intx,s,t,d; scanf("%d",&x); s=x%60; t=(x/60)%60; d=(x/60)/60; printf("%d时%d分%d秒",d,t,s);}三个数的交换#include<stdio.h>voidmain(){ inta,b,c,t; scanf("%d%d%d",&a,&b,&c); printf("Theoriginalnumber:a=%d,b=%d,c=%d\n",a,b,c);t=a,a=b,b=t;t=a,a=c,c=t; printf("afters",a,b,c);}switch语句的运用#include<stdio.h>main(){ inta,m; printf("pleaseinputanumber:"); scanf("%d",&a); switch(a/10) { case10: case9:m=5;break; case8:m=4;break; case7:m=3;break; case6:m=2;break; default:m=1; } printf("m=%d",m);}判断奇数和偶数#include<stdio.h>main(){ intx; printf("Pleaseinputanumber:"); scanf("%d",&x); if(x%2==0) printf("thisisaoushu!"); else printf("thisisajishu!");}小写改大写，若是大写则不变include<stdio.h>main(){charc1,c2;printf("Inputaletter\n");scanf("%c",&c1);c2=('a'<=c1&&c1<='z')?(c1-'a'+'A'):c1;printf("%c",c2);getchar();return0;}输入一个数，输出这个数是几位数#include<stdio.h>main(){ intx,n; printf("pleaseinputanumber:"); 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>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=%d\n",len);printf("Reverseis%d",temp);}打印水仙花数#include<stdio.h>main(){ intx,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"stdio.h"main(){ intk,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(){ intsum,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项和#include<stdio.h>main(){ floats,t; intn,i,fz,fm; s=0; fz=2; fm=1; printf("Entern:"); 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=%f\n",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为任意/*用标记值来指示数据输入的结束*/#include<stdio.h>main(){ floataverage,total; intcounter,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:"); scanf("%d",&score); } if(counter!=0) { average=total/counter; printf("全班平均成绩为：%.2f\n",average); } else printf("没有输入成绩\n"); return0; }求二元一次方程的根#include<stdio.h>#include<math.h>main(){ floata=4,b=-40,c=91; floatx1,x2; floatdelta; delta=sqrt(b*b-4.0*a*c); x1=(-b+delta)/(2.0*a); x2=(-b-delta)/(2.0*a); printf("x1=%fx2=%f\n",x1,x2);}if语句的运用#include<stdio.h>main(){ inta,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<stdio.h>main(){ inty0,m0,d0,y1,m1,d1,age; printf("\npleaseinputbirthday(yyyy/mm/dd):"); scanf("%d/%d/%d",&y0,&m0,&d0); printf("\npleaseinputcurrentday(yyyy/mm/dd):"); scanf("%d/%d/%d",&y1,&m1,&d1); if((m1>m0)||(m1=m0&&d1>=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>voidss*x,int*y);main(){ inta=10,b=20; printf("befores\n",a,b); ss); printf("afters\n",a,b);}voidss*x,int*y){ intt; 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) returnpx; returnpy;}main(){ floatx=10.0,y=20.0,*a=&x,*b=&y; printf("*a=%f,*b=%f,max=%f\n",*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<stdio.h>voidLower2Upper(char*str){ char*p=str; while(*p!=0) { if(*p<='z'&&*p>='a') *p=*p-32; p++; }}main(){ chars[10]="Hello!"; inti; Lower2Upper(s); for(i=0;i<10;i++) printf("%c",s[i]);}计算一个字符在一个字符串中出现的次数#include<stdio.h>intcount(charch,char*str){ char*p=str; intnum=0; while(*p!='\0') if(*p++==ch) num++; returnnum;}main(){ charah='a'; chars[]="haowareayou";printf("thenumberis:"); printf("%d\n",count('a',s));}删除一维数组中所有相同的数#include<stdio.h>voidunique(int*a,int*n){ intk=1; inti,m; m=a[0]; for(i=0;i<*n;i++) { if(a[i]>m) { a[k++]=a[i]; m=a[i]; } } *n=k;}main(){ inta[10]; intn=10,i; printf("inputalistnumber:"); for(i=0;i<n;i++) scanf("%d",&a[i]); printf("Beforedelete:...\n"); for(i=0;i<n;i++) printf("%d",a[i]); unique(a,&n); printf("afterdelete\n"); for(i=0;i<n;i++) printf("%d",a[i]); printf("\n");}将字符串按字典顺序输出#include<stdio.h>#include<string.h>#defineN5voidsort(char*name[],intn);voidprn(char*name[],intn);voidmain(){ char*name[]={"China","America","Australia","France","German"}; sort(name,N); prn(name,N);}voidsort(char*name[],intn){ char*pt; inti,j,k; for(i=0;i<n-1;i++) { k=i; for(j=i+1;j<n;j++) if(strcmp(name[k],name[j])>0) k=j; if(k!=i) { pt=name[i]; name[i]=name[k]; name[k]=pt; } }}voidprn(char*name[],intn){ inti; for(i=0;i<n;i