初学C语言常用简单程序代码

1/16初学C语言常用简单程序代码素数的筛选#includestdio.h#includemath.h#defineN1000intmain(intargc,char*argv[]){inti,j,num[N];for(i=0;iN;i++)num[i]=i+1;for(i=1;i(int)sqrt((double)N);i++){if(num[i]){for(j=i+1;jN;j++){if(num[j])if(num[j]%num[i]==0)num[j]=0;}}}for(i=1;iN;i++)if(num[i])printf(%d,num[i]);return0;}输出时分秒#includestdio.h2/16main(){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#includestdio.hvoidmain(){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(afterswap:a=%d,b=%d,c=%d,a,b,c);}switch语句的运用#includestdio.hmain(){inta,m;printf(pleaseinputanumber:);scanf(%d,&a);switch(a/10){case10:case9:m=5;break;3/16case8: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#includestdio.hmain(){intx;printf(Pleaseinputanumber:);scanf(%d,&x);if(x%2==0)printf(thisisaoushu!);elseprintf(thisisajishu!);}小写改大写，若是大写则不变includestdio.hmain(){charc1,c2;printf(Inputaletter\n);scanf(%c,&c1);c2=('a'=c1&&c1='z')?(c1-'a'+'A'):c1;printf(%c,c2);getchar();return0;4/16}输入一个数，输出这个数是几位数#includestdio.hmain(){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#includestdio.hintmain(){intnum;intlen=0;inttemp=0;printf(Pleaseinputanumber:\n);scanf(%d,&num);while((num%10)!=0){temp=temp*10+(num%10);len++;5/16num=num/10;}printf(length=%d\n,len);printf(Reverseis%d,temp);}打印水仙花数#includestdio.hmain(){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#includestdio.hmain(){intk,flag,n=0;for(k=1980;k=2880;k++)6/16{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#includestdio.hmain(){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#includestdio.hmain(){floats,t;7/16intn,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*/#includestdio.hmain(){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*/{8/16total=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);}elseprintf(没有输入成绩\n);return0;}求二元一次方程的根#includestdio.h#includemath.hmain(){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);9/16}if语句的运用#includestdio.hmain(){inta,b,c,s,w,t;s=w=t=0;a=-1;b=c=3;if(c0)s=a+b;if(a=0){if(b0)if(c=0)w=a-b;}elseif(c0)w=a-b;elset=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#includestdio.hmain(){inty0,m0,d0,y1,m1,d1,age;10/16printf(\npleaseinputbirthday(yyyy/mm/dd):);scanf(%d/%d/%d,&y0,&m0,&d0);printf(\npleaseinputcurrentday(yyyy/mm/dd):);scanf(%d/%d/%d,&y1,&m1,&d1);if((m1m0)||(m1=m0&&d1=d0))age=y1-y0;elseage=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#includestdio.hvoidsswap(int*x,int*y);main(){inta=10,b=20;printf(beforeswap:a=%d,b=%d\n,a,b);sswap(&a,&b);printf(afterswap:a=%d,b=%d\n,a,b);}voidsswap(int*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#includestdio.hfloat*f(float*px,float*py)11/16{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#includestdio.hvoidLower2Upper(char*str){char*p=str;while(*p!=0){if(*p='z'&&*p='a')*p=*p-32;p++;}}main(){chars[10]=Hello!;12/16inti;Lower2Upper(s);for(i=0;i10;i++)printf(%c,s[i]);}计算一个字符在一个字符串中出现的次数#includestdio.hintcount(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#includestdio.h13/16voidunique(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;in;i++)scanf(%d,&a[i]);printf(Beforedelete:...\n);for(i=0;in;i++)printf(%d,a[i]);unique(a,&n);printf(afterdelete....\n);for(i=0;in;i++)printf(%d,a[i]);printf(\n);}14/16将字符串按字典顺序输出#includestdio.h#includestring.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;in-1;i++){k=i;for(j=i+1;jn;j++)if(strcmp(name[k],name[j])0)k=j;if(k!=i){pt=name[i];name[i]=name[k];name[k]=pt;}}}15/16voidprn(char*name[],intn){inti;for(i=0;in;i++)printf(%s\n,name[i]);}有n个学生，每个学生考m门课程，要求编一程序，能检查n个学生有无不及格的课程，如果有某一学生有一门或一门以上课程不及格，就输出该学生的号码和其全部成绩#includestdio.h#defineN5#defineM4,intcol);voidprt(float*s,intno,intlen);main(){floata[N][M]={{78,99,89,87},{67,59,87,77},{86,53,59,95},{77,88,57,95},{78,75,87,95}};score(a,N,M);}voidscore(f