C语言程序笔记

1、1比较大小两个数/谭浩强书176主函数里的调用max函数有问题并且运行窗口一闪而过(1)#include #include int main ()float max(float x,float y);float a,b,c;printf(please input two numbersn);scanf(%f,%f,&a,&b);c = max(a,b);/sleep(10);printf(the lagest number is:n);return 0;float max(float x,float y)float z;if(xy)z = x;elsez = y;return z;(2) 正确

2、的解答方式，运行窗口最后可以停住#include #include float max(float x,float y);int main ()float a,b,c;printf(please input two numbersn);scanf(%f,%f,&a,&b);c = max(a,b);/sleep(10);printf(the lagest number is:n);while(1);return 0;float max(float x,float y)float z;if(xy)z = x;elsez = y;return z;2/水仙花数#includeint main()i

3、nt num,a,b,c;while(scanf(%d,&num)if(num!=0)a=num%10;num/=10;b=num%10;c=num/10;if(a*a*a+b*b*b+c*c*c=num)printf(Yesn);elseprintf(Non);else break; return 0;3/输出小于某个数的奇数和偶数（1）#includeint main()int n;scanf(%d,&n);int a;while(n-)scanf(%d,&a);for(int i=1;i=a;i+=2)printf(%d ,i);puts();for(int i=2;i=a;i+=2)p

4、rintf(%d ,i);puts();（2）#includeint main()int a;while(a%2!=1)while(1)scanf(%d,&a);for(int i=1;i=a;i+=2)printf(%d ,i);puts();for(int i=2;i=a;i+=2)printf(%d ,i);puts();(3)/main函数簓里?：阰while语?句?应畖该?包悒?括f和fou语?句?#includeint a;int main() while(1)scanf(%d,&a);if(a%2!=1) for(int i=1;i=a;i+=2)printf(%d ,i);pu

5、ts(); for(int i=2;i=a;i+=2)printf(%d ,i);puts(); 4比较五个数的大小并输出最大和最小值#includeusing namespace std;int main()int a,b,c,d,e,f,g;cinabcde;if(ac)f=c;if(fd)f=d;if(fe)f=e;if(gc)g=c;if(gd)g=d;if(ge)g=e;coutf gendl;return 0;（1）#include int s5; int t; int i;int main() for(i=0;i5;i+) scanf(%d,&si); for(int m=1;m

6、5;m+) for(int n=0;nsn+1) t=sn+1; sn+1=sn; sn=t; printf(%d %dn,s0,s4); while (1);return 0; 5/输入成绩，系统分配等级，本例题中N代表总人数#includeint main()int n,score;scanf(%d,&n);while(n-)scanf(%d,&score);switch(score/10)case 10:printf(An);break;case 9:printf(An);break;case 8:printf(Bn);break;case 7:printf(Cn);break;case

7、 6:printf(Dn);break;default:printf(En);break;while(1);return 0;（2）#includeint main()int i,n,m;scanf(%d,&n);for(i=1;i=90)&(m=80)&(m=70)&(m=60)&(m=0)&(m=59)printf(En);while(1);return 0;6鸡兔同笼问题#include int chikNum,rabNum,staNum;int inputHead,inputFeet;int main()scanf(%d,&staNum);for(int i=0;i0)&(rabNum

8、0)printf(%d,%dn,chikNum,rabNum);elseprintf(No answern);while(1);return 0;7ascll排序(1)int main() char a,b,c;while(scanf( %c%c%c,&a,&b,&c)!=EOF) /加个?空?格?，?第台?二t个?也?一?样if(ab)&(bc)printf(%c %c %c,a,b,c);if(ac)&(cb)printf(%c %c %c,a,c,b);if(ba)&(ac)printf(%c %c %c,b,a,c);if(bc)&(ca)printf(%c %c %c,b,c,a);

9、if(ca)&(ab)printf(%c %c %c,c,a,b);if(cb)&(ba)printf(%c %c %c,c,b,a); return 0;(2)#include#includeint main()int n,i,j;char a100,t;scanf(%d,&n);gets(a);while(n-)gets(a);for(i=0;istrlen(a);i+)for(j=0;jstrlen(a);j+)if(aiaj)t=ai;ai=aj;aj=t;for(i=0;istrlen(a);i+)printf(%c ,ai);printf(n);return 0;8注意第二个sca

10、nf函数里的空格，如果没有空格，那么输出的结果会受【enter？键的影响】因为line feed的ascll值是10，而（space）的ascll值是32.档按下enter时，那两个键会影响最后的输出结果，干扰。scanf(%c,&c) 与 scanf( %c,&c)，后者只是在%前多了个空格，似乎没有什么区别，但使用起来区别是很大的。scanf()作单字符输入时规定只接收一个字符，但它却把回车符也作为字符对待的。这就造成程序中只有一个输入字符的scanf()语句时，问题还不大，但如果后面还跟着第二个scanf()字符输入语句，这个scanf()就把前面输入的驾车符当作输入字符了。这就在输入逻

11、辑上造成了混乱，达不到人们预期的愿望。有了这个空格，因为scanf()是跳过空格读字符的，就回避了这个问题。实践证明，这个空格放在%c后面也不能达到目的。应当说，这也是比较巧妙的应用！#include int groNum;char c1;int main ()printf(please enter:n);scanf(%d,&groNum);for(int i=groNum;i0;i-)scanf( %c,&c1);printf(%dn,c1);while(1);return 0;9gets（）函数可以读入空格，而scanf()不能。scanf(%s,c); 与gets(c);有什么区别呢？为

12、什么加上getchar（）；就正确呢，不加，后面的数组只能接收三个呢？scanf(%s,c)？与gets(c);有什么区别呢？scanf(%s,c);接受字符是以空格或者制表符或者回车分隔的,不会接受回车gets（），是以为回车分隔的。不加getchar();的时候scanf(%s,c); 时候输入的回车被第一个gets接收了，所以后面就只能接收三个了。提问者评价gets()，回车后，这时回车符会转换为0,但scanf()不会将回车符转换为0,会给下一个字符变量。#include #includeint main() typedef char CHARR20; CHARR c, d4; int

13、 i;scanf(%s,c); puts(c);printf(接收数组：);getchar();for(i=0;i4;i+)gets(di);for(i=0;i4;i+)puts(di); return 0;10阶乘问题（1）#includeint i,j,sum,a,b;int main()scanf(%d,&b);for(j=1;j=b;j+)scanf(%d,&a);sum = 1;for(i=1;i=a;i+)sum = sum * i;/sum = sum + sum;printf(%dn,sum);while(1);return 0;（2） 将原来的每个数相乘变为i不大于n的所有奇

14、数相乘例如：5!=1*3*5. #includeint main()int factorial(int m);int n, a;scanf(%d,&n);while(n-)scanf(%d,&a);printf(%dn, factorial(a) );while(1);return 0; int factorial(int m)int sum1, sum2, i,j;sum1 = 0; for(i = 1; i = m; i+)sum2 = 1;for(j = 1; j = i; j = j + 2)sum2 =sum2 * j;sum1 = sum1 + sum2;return sum1;1

15、1如题，输入一个日期，格式如：2010 10 24 ，判断这一天是这一年中的第几天。#includeint main()int a,b=0,c,y,m,d,fib;scanf(%d,&a);while(a-)scanf(%d %d %d,&y,&m,&d);if(y%400=0|y%100!=0&y%4=0)fib=29;else fib=28;for(c=1;c=m;c+)switch(c-1)case 1:case 3:case 5:case 7:case 8:case 10:b+=31;break;case 2:b+=fib;break;case 4:case 6:case 9:case

16、 11:b+=30;break;b+=d;printf(%dn,b);b=0;return 0;12 让第一个数码管亮，显示数字为二#include sbit duan =P10;sbit wei =P11;void main()while(1)wei = 1;P0 = 0x01;wei = 0;duan = 1;P0 = 0xc4;duan = 0;/while(1);13C51六个数码管分别从0到七流水线水显示#include #define uchar unsigned char#define uint unsigned int sbit duan = P10;sbit wei = P1

17、1;unsigned char Num=0xa0,0xf9,0xc4,0xd0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xa6,0xc1,0x86,0x8e;/void delay (uint);void main ()while(1)duan = 1;P0 = 0xf9;duan = 0;P0 = 0xff;wei = 1;P0 = 0x01;wei = 0;delayms(500);duan = 1;P0 = 0xc4;duan = 0;P0 = 0xff;wei = 1;P0 = 0x02;wei = 0;delayms(500);duan =

18、1;P0 = 0x99;duan = 0;P0 = 0xff;wei = 1;P0 = 0x04;wei = 0;delayms(500);duan = 1;P0 = 0xd0;duan = 0;P0 = 0x82;wei = 1;P0 = 0x08;wei = 0;delayms(500);duan = 1;P0 =0x92;duan = 0;P0 = 0xff;wei = 1;P0 = 0x20;wei = 0;delayms(500);duan = 1;P0 = 0xf8;duan = 0;P0 = 0xff;wei = 1;P0 = 0x40;wei = 0;delayms(500);

19、void delayms(uint xms) uint i,j; for (i = xms;i0;i-) for (j = 110;j0;j-); 14实例 独立键盘 #include#define unchar unsigned char #define uint unsigned intsbit key1 = P34;sbit key2 = P35;sbit key3 = P36;sbit key4 = P37;sbit duan = P26;sbit wei = P27;uchar code table=0xa0,0xf9,0xc4,0xd0,0x99,0x92,0x82,0xf8,0x

20、80,0x90,0x88,0x83,0xa6,0xc1,0x86,0x8e;void delayms(uiint);void display (uchar numdis)uchar shi,ge;shi = numdis/10;ge = numdis%10;duan = 1;P0 = tableshi;duan = 0;P0 = 0xff;wei = 1;P0 = 0xfe;wei = 0;delayms(5);duan = 1;P0 = tablege;duan = 0;P0 = 0xff;wei = 1;P0 = 0xfd;wei = 0;delayms(5);void delayms(u

21、int xms)uint i,j;for(i=xms;i0;i-) for(j=110;j0;j-);void init () TMOD = 0x01; TH0 = (65536-45872)/256; TH1 = (65536-45872)%256; EA = 1; ET0 = 1;void keyscan()if(key1 = 0) delayms(10); if(key1=0) num+; if(num=60) num=0; while(!key1); if(key2= 0) delayms(10); if(key1=0) num+; if(num=60) num=0; while(!k

22、ey2); if(key3 = 0) delayms(10); if(key3=0) num+; if(num=60) num=0; while(!key1); if(key4 = 0) delayms(10); if(key4=0) num+; if(num=60) num=0; while(!key1); void main()init();while(1)keyscan();display(num);void T0_time()interrupt 1 TH0 = (65536-45872)/256; TH1 = (65536-45872)%256; numt0+; if(numt = 2

23、0) numt0 = 0;num+;if(num = 60)num = 0; 15输入两个正整数m,n.(m,n,都是三位数);输出m,n,相加时需要进位多少次。方一：#includeint main()int m,n;scanf(%d %d,&m,&n);while(m|n)int a3,b3;for(int i=0;i3;i+)ai=m%10;bi=n%10;m/=10;n/=10;int flag=0;int count=0;for(int i=0;i=10)flag=1;count+;elseflag=0;printf(%dn,count);scanf(%d %d,&m,&n);whi

24、le(1);return 0;方二：# main()03.04.int a,b,c,d,e,f,n,m,i;05.for(;)06.07.scanf(%d%d,&n,&m);08.if(n=0&m=0) /两数相与，结果存入下09.return 0;/如果两个数都是零，则输出零10.else11.12.i=0;13.a=n/100;b=n%100/10;c=n%10;14.d=m/100;e=m%100/10;f=m%10;15.if(c+f=10)16.i+=1;b+=1;17.if(b+e=10)18.i+=1;a+=1;19.if(a+d=10)20.i+=1;

25、/c和f是两个数的个位，所以当他们的和大于十时，用i来记录全程的进位，/并且，把这个个位的进位付给十位，同理十位和百位的加和也是类似的思路21.printf(%dn,i);22.23.24.return 0;25.16描述相传韩信才智过人，从不直接清点自己军队的人数，只要让士兵先后以三人一排、五人一排、七人一排地变换队形，而他每次只掠一眼队伍的排尾就知道总人数了。输入3个非负整数a,b,c ，表示每种队形排尾的人数（a3,b5,c7），输出总人数的最小值（或报告无解）。已知总人数不小于10，不超过100 。输入输入3个非负整数a,b,c ，表示每种队形排尾的人数（a3,b5,c7）。例如,输入

26、：2 4 5输出输出总人数的最小值（或报告无解，即输出No answer）。实例，输出：89 方一：#include02.using namespace std;03.int main()04.05.int a,b,c;06.cinabc;07.int n=(a*70+b*21+c*15)%105;08.if(n100|n10) coutNo answerendl;09.else coutnendl;10. 11.方二：#includeusing namespace std;int main() int x, a, b, c;Scanf(“%d,%d,%d”,&a,&b&c);cin a b

27、c;for(x = 0; x = 100; x+) if(x % 3 = a & x % 5 = b & x % 7 = c) /a%b就是计算a除以b得出的余数。 cout x 100 & x 10)cout No answer endl;/输出No answer的值，然后在换到下一行。【VC+中using namespace std有什么用的】std 是一个命名空间.不同的命名空间可以有相同的类名被定义 .using namespace std;就是指明下面的程序使用std,如果不用这句指明的话就要用std:string(string是std空间中定义的也可以在全局空间中定义,只要名字空间

28、不一样即可.).否则可以默认名字空间中有std.便不用std:来修饰它是C+新标准中有的，解决多人作编大程序时名字冲突问题。比如A B两个班都有叫张三的人,你要使用A班的张三,必然要先指名是A班这个名字空间(namespace),然后你对张三的所有命令才能达到你的预想,不会叫错人 如果你用#include就不需写这句话（旧标准）。但是如果你用#include就必须要写。17(1)#include#includeint main()int N;scanf(%d,&N);while(N-)double x1,y1,x2,y2;double distance;scanf(%lf%lf%lf%lf,&

29、x1,&y1,&x2,&y2);double x=pow(x1-x2,2);double y=pow(y1-y2,2);distance=sqrt(x+y);/distance=sqrt(pow(x1-x2,2)+pow(y1-y2,2);printf(%.2lfn,distance);return 0;(2)#include int i,n,a,b,c,d;int main ()int sum=0;/printf(please enter n:n);/scanf(%d,&n);/for(i=0;in;i+)/printf(please enter four words:n);scanf(%d

30、 %d %d %d,&a,&b,&c,&d);if(a != c) | (b != d)sum = (a-c)*(a-c)+(b-d)*(b-d)(2);printf(%d/n,sum);elseprintf(sum = 0);/while(1);return 0;18 51单片机。用定时器0的方式0实现第一个发光二极管以200ms间隔闪烁，用定时器一的方式实现数码管前两位59s循环及时。#include #define uchar unsigned char #define uint unsigned intsbit duan = P10;sbit wei = P11;sbit led1 =

31、 P12;uchar code table= 0xa0,0xf9,0xc4,0xd0, 0x99,0x92,0x82,0xf8, 0x80,0x90,0x88,0x83, 0xa6,0xc1,0x86,0x8e;void delayms(uint);void display(uchar,uchar); uchar num,num1,num2,shi,ge;void main () TMOD = 0x11; TH0 = (65536-45872)/256; TL0 = (65536-45872)%256; TH1 = (65536-45872)/256; TL1 = (65536-45872)%

32、256; EA = 1; ET0 = 1; ET1 = 1; TR0 = 1; TR1 = 1; while(1) display(shi,ge); void display(uchar shi,uchar ge)duan = 1;P0 = tableshi;duan = 0;P0 = 0xff;wei = 1;P0 = 0xf9 ;wei = 0;delayms(5);duan = 1;P0 = tablege;duan = 0;P0 = 0xff;wei = 1;P0 = 0x88;wei = 0;delayms(5);void delayms(uint xms) uint i,j; fo

33、r (i=0;ixms;i+) for(j=0;j110;j+); void T0_time()interrupt 1 TH0 = (65536-45872)/256; TL0 = (65536-45872)%256; num1+; if(num1=4) num1=0;led1=led1; void T1_time()interrupt 3 TH0 = (65536-45872)/256; TL0 = (65536-45872)%256; num2+; if(num2=60) num2=0;/led2=led2;num+;if(num=60)num=0;shi=num/10;ge=num%10

34、; 19/在数码管上电时，数码管不显示，顺序按下矩阵键盘后在数码管上依次显示0到F，六个数码管同时静态显示即可/宏定义，声明参量并且定义管口#include #define uchar unsigned char #define uint unsigned intsbit duan = P10;sbit wei = P11;/无符号字符数组，code相当于C语言中的const的常量数组uchar code table=0xa0,0xf9,0xc4,0xd0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xa6,0xc1,0x86,0x8e /十六个数码管;

35、/定义一个人延时函数void delayms (uint xms) uint i,j; for(i=0;ixms;i+) for(j=0;j110;j+); /声明一个显示函数，显示函数仅仅选送段选数据void display(uchar num) P0=tablenum;/选送函数只选送段选数据 duan = 1; duan = 0; /矩阵键盘函数void matrixkeyscant() uchar temp,key; P3 = 0xfe;/p3管口，将第一行线置一 temp = P3; temp = temp&0xf0;/进行与运算，主要作用是判断temp的 /高四位是否有低电平,高四

36、位实际反应列线 if(temp!=0xf0) delayms(10);temp = P3;temp = temp&0xf0;if(temp!=0xf0)/重新读P3口的数据。重新进行与运算。/若temp仍然不等于零，则确认键盘按下temp = P3;switch(temp)case 0xee:key = 0;break;case 0xde:key = 1;break;case 0xbe:key= 2;break;case 0x7e:key = 3;break;/在判断完按键序号后，还需要等待按键被释放while(temp!=0xf0)temp = P3;temp = temp&0xf0;dis

37、play(key); P3 = 0xfd;/p3管口，将第一行线置一 temp = P3; temp = temp&0xf0;/进行与运算，主要作用是判断temp的 /高四位是否有低电平,高四位实际反应列线 if(temp!=0xf0) delayms(10);temp = P3;temp = temp&0xf0;if(temp!=0xf0)/重新读P3口的数据。重新进行与运算。/若temp仍然不等于零，则确认键盘按下temp = P3;switch(temp)case 0xed:key = 4;break;case 0xdd:key = 5 ;break;case 0xbd:key= 6;b

38、reak;case 0x7d:key = 7;break;/在判断完按键序号后，还需要等待按键被释放while(temp!=0xf0)temp = P3;temp = temp&0xf0;display(key); P3 = 0xfb;/p3管口，将第一行线置一 temp = P3; temp = temp&0xf0;/进行与运算，主要作用是判断temp的 /高四位是否有低电平,高四位实际反应列线 if(temp!=0xf0) delayms(10);temp = P3;temp = temp&0xf0;if(temp!=0xf0)/重新读P3口的数据。重新进行与运算。/若temp仍然不等于零

39、，则确认键盘按下temp = P3;switch(temp)case 0xeb:key = 8;break;case 0xdb:key = 9;break;case 0xbb:key= 10;break;case 0x7b:key = 11;break;/在判断完按键序号后，还需要等待按键被释放while(temp!=0xf0)temp = P3;temp = temp&0xf0;display(key); P3 = 0xf7;/p3管口，将第一行线置一 temp = P3; temp = temp&0xf0;/进行与运算，主要作用是判断temp的 /高四位是否有低电平,高四位实际反应列线 i

40、f(temp!=0xf0) delayms(10);temp = P3;temp = temp&0xf0;if(temp!=0xf0)/重新读P3口的数据。重新进行与运算。/若temp仍然不等于零，则确认键盘按下temp = P3;switch(temp)case 0xe7:key = 12;break;case 0xde:key = 13;break;case 0xb7:key= 14;break;case 0x77:key =15 ;break;/在判断完按键序号后，还需要等待按键被释放while(temp!=0xf0)temp = P3;temp = temp&0xf0;display(

41、key); /声明主函数void main () P0=0; duan=1; duan =0; P0=0xe0; wei=1; wei=0; while(1) matrixkeyscant(); 20aaaaa#include #define uchar unsigned char#define uint unsigned charsbit key = P20;sbit duan = P10;sbit wei = P11;uchar code table=0xa0,0xf9,0xc4,0xd0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xa6,0xc1,

42、0x86,0x8e;uchar num,numt0;void delayms(uint);void display(uchar numdis) duan = 1; P0 = tablenumdis; duan = 0; P0 = 0xff; wei = 1;P0 = 0xf9; wei = 0; delayms(5);void delayms(uint xms) uint i,j; for(i=0;ixms;i+) for(j=0;j110;j+); void init() TMOD = 0X01; TH0 = (65536-45872)/256; TL0 = (65536-45872)%256; EA = 1; ET0 = 1; void keyscant() if(key = 0) delayms(10);if(key = 0) num = 60; num-; wh