c語言前四章例題

1、第一章：分支導例：輸入生日并顯示#include <stdio.h> /*編譯預處理命令*/int main( ) /*定義了一個名字為main的函數(shù)*/int month, day; /*定義變量month和day*/ printf("Enter the month and the day of your birthday:"); scanf("%d%d", &month,&day); printf(“Your birthday is :%d月%d日n", month, day);return 0;導例：匯率換算#

2、include <stdio.h> main( ) int rmb; /*定義整型變量，存放人民幣值*/ float rate; /*定義浮點型放匯率值*/ float dollar; /*定義浮點型放美元值*/ rate=0.1642; /*對變量rate賦值*/ printf("rmb="); scanf(“%d”,&rmb); /*接收用戶輸入*/ dollar=rmb*rate; /*匯率換算*/ printf("￥%d can exchange $%.2fn",rmb,dollar); /*調(diào)用printf()函數(shù)輸出結果*

3、/導例：字符加密#include <stdio.h>main () char ch; /*定義一個字符變量ch*/  ch=getchar(); /*調(diào)用getchar()函數(shù)，從鍵盤上輸入一個字符，賦值給ch*/ ch=ch+3; /*為字符ch加密 */ putchar(ch); /*調(diào)用putchar()函數(shù)，輸出加密后的ch*/  putchar(n); /*輸出回車換行符*/導例：考核通過了嗎#include <stdio.h> main ()int score1，score2，score3; /*定義成績變量*/ printf("

4、;請輸入三項考核成績：");scanf("%d%d%d",&score1,&score2,&score3);printf(“第一項考核果：%dn",score1>=60);printf("第二項考核果：%dn",score2>=60);printf("第三項考核果：%dn",score3>=60);printf("綜合考核結果：%dn",(score1>=60) && (score2>=60) && (scor

5、e3>=60);算術運算符算術運算符用于各種數(shù)值運算，包括5個二元運算符：加（+）、減（-）、乘（*）、除（/）、求余（%），和2個一元運算符：自增（+）、自減（-）。判斷數(shù)字的奇偶性#include <stdio.h> int main(void) int number; printf("Enter a number: "); scanf("%d", &number); if(number % 2 = 0) printf(“偶數(shù). n"); else printf(“奇數(shù). n"); return 0;今年

6、是閏年嗎？#include <stdio.h> main( ) int year;  printf("Enter year:"); scanf("%d", &year);  if(year%4=0&&year%100!=0|year%400=0) /*閏年的條件*/ printf("YESn"); else printf("NOn"); 求解一元二次方程從鍵盤輸入一元二次方程ax2+bx+c=0的3個系數(shù)a,b,c，編程計算該方程的解，并輸出之#in

7、clude <stdio.h>#include <math.h>main()int a, b, c, s; double x1,x2 ;printf("Enter 3 integers:");scanf(“%d%d%d”, &a, &b, &c);s=b*b-4*a*c ;/*條件判斷，輸出結果*/if (s>0) x1=(-b+sqrt(s)/(2*a) ; x2=(-b-sqrt(s)/(2*a) ; printf("x1=%f, x2=%fn", x1,x2) ; else if (s=0) x

8、1=x2=(-b)/(2.0*a) ; printf("x=%fn", x1) ; else printf(“No solutionn”);求解簡單的四則運算表達式輸入一個形式如“操作數(shù) 運算符 操作數(shù)”的四則運算表達式，根據(jù)輸入的運算符，做相應運算，輸出運算結果。使用if語句實現(xiàn)四則運算# include <stdio.h>int main(void) double value1, value2; char op; /*定義字符型的變量*/ scanf("%lf%c%lf", &value1, &op, &value

9、2); if(op = '+') printf("=%.2fn", value1 + value2); else if(op = '-') printf("=%.2fn", value1 - value2); else if(op = '*') printf("=%.2fn", value1 * value2); else if(op = '/') printf("=%.2fn", value1 / value2); else printf("

10、;Unknown operatorn"); return 0;使用switch語句實現(xiàn)四則運算# include <stdio.h>int main(void) double value1, value2; char op; scanf("%lf%c%lf", &value1, &op, &value2); switch (op) case '+': printf("=%.2fn", value1 + value2); break; case '-': printf("

11、;=%.2fn", value1 - value2); break; case '*': printf("=%.2fn", value1 * value2); break; case '/': printf("=%.2fn", value1 / value2); break; default:printf("Unknown operatorn"); break; return 0;計算存款利息銀行對整存整取存款期限不同對應的存款利率也不同，鍵盤輸入存款本金和存期，計算到期時的利息及利息與本金的

12、和。當前整存整取年息利率：一年：3.25% 二年：3.75% 三年：4.25% 五年：4.75%#include <stdio.h>main( ) double money, rate, rest, total; int time;  printf("輸入本金:"); scanf("%lf",&money); printf("請輸入存期:"); scanf("%d",&time); /*使用switch語句實現(xiàn)利率的選擇*/ switch(time) case 1:

13、rate=0.0325; break; case 2: rate=0.0375; break; case 3: rate=0.0425; break; case 5: rate=0.0475; break; default: rate=0; rest=money*rate*time; total=money+rest;  printf("到期利息：%.2fn",rest); printf("本息合計：%.2fn",total);輸入三條邊，判斷它們能否構成三角形，若能則指出是何種三角形。方法一#include <stdio.h>ma

14、in()float a,b,c;printf("請輸入三條邊的值：n");scanf("%f%f%f",&a,&b,&c);if(a<(b+c)&&(b<(a+c)&&(c<(a+b) if(a =b|b=c|a=c) if (a=b&&b=c) printf("可以構成等邊三角形!n"); else printf("可以構成等腰三角形!n"); else printf("可以構成不等邊三角形!n");el

15、se printf("不能構成三角形!n");方法二#include <stdio.h>main()float a,b,c;printf("請輸入三條邊的值：n");scanf("%f%f%f",&a,&b,&c);if(b+c)<=a)|(a+c)<=b)|(a+b)<=c)printf("不能構成三角形!n");elseif(a !=b&&b!=c&&a!=c) printf("可以構成不等邊三角形!n")

16、;else if (a=b&&b=c) printf("可以構成等邊三角形!n"); else printf("可以構成等腰三角形!n");第二章：循環(huán)2.2 求解n!n! = 1×2×3×4××n用for語句#include <stdio.h>main( ) int i, n,fact; printf ("input n:");scanf ("%d", &n);fact=1;for(i=1;i<=n;i+) fact =

17、fact*i;printf(“%d! = %dn", n, fact);return 0;用while語句#include <stdio.h>main( ) int i, n,fact; printf ("input n:"); scanf ("%d", &n); fact=1; i=1; while(i<=n) fact = fact*i; i+; printf(“%d! = %dn", n, fact);return 0;2.1 求偶數(shù)和求解100以內(nèi)所有偶數(shù)的和 。sum=2+4+6+#include

18、<stdio.h>int main(void)int i, sum = 0;  for(i = 1; i <= 100; i+) if (i%2 = 0) sum = sum + i; printf(“%dn", sum); return 0; while 和 for 的比較用 forfor (i = 1; i <= n; i+) sum = sum + i; 用 whilei = 1; /循環(huán)變量賦初值while (i <= n) /循環(huán)條件 sum = sum + i; i+; /循環(huán)變量的改變2.3求解最大公約數(shù)輸入兩個整數(shù)，求解這兩個數(shù)

19、的最大公約數(shù)。最大公約數(shù)：是能夠同時整除這兩個整數(shù)的最大的正整數(shù)。#include <stdio.h>main( ) int num1,num2; int a,b,temp; printf("Input num1 & num2:"); scanf("%d%d", &num1, &num2) ; a=num1; b=num2; while (b!=0 ) temp = a%b ; a = b; b = temp ; if (num1!=0&&num2!=0) printf("%dn",

20、a); 2.5 統(tǒng)計一個整數(shù)的位數(shù)int main(void) int count, number; count = 0;printf("Enter a number: ");scanf ("%d", &number) ;if (number < 0) number = -number; do number = number / 10; count +; while (number != 0);printf("It contains %d digits.n", count); return 0;2.4 用格里高利公式求的

21、近似值 #include <stdio.h>#include<math.h> main( ) double item, sum, pi; int flag, i; i = 1; flag=1; sum=0; item=1； do sum = sum + item; flag = -flag ; i = i+2 ; item = flag*1.0/i ; while ( fabs (item) >= 0.0001 )； pi = sum * 4 ; printf("pi = %fn", pi); 從鍵盤輸入一批學生的成績，計算平均成績，并統(tǒng)計不及

22、格學生的人數(shù)。#include <stdio.h>Int main(void) int num; double grade, total; num = 0; total = 0;printf(“Enter grades: n"); scanf("%lf", &grade); /* 輸入第1個數(shù)*/while (grade >= 0) /* 輸入負數(shù)，循環(huán)結束 */ total = total + grade; num+; if(grade<60) count+; scanf (“%lf”, &grade);if(num !=

23、 0) printf(“Grade average is %.2fn", total/num); printf("Number of failures is %dn", count); else printf(“ Grade average is 0。n"); return 0;輸入一批學生的成績，求最高分(do-while)#include <stdio.h>int main(void) int mark, max; max = -1; /* 給max賦一個小初值 */ printf(“Enter marks: "); do sc

24、anf ("%d", &mark ); if (max < mark) max = mark; while(mark >= 0); printf("Max = %dn", max);輸入一批學生的成績，求最高分(for)#include <stdio.h>int main(void) int i, mark, max, n; printf("Enter n: "); scanf ("%d", &n); printf("Enter %d marks: ",

25、n); scanf ("%d", &mark); /* 讀第一個成績 */ max = mark; /* 假設第一個成績最高分 */ for (i = 1; i < n; i+ ) scanf ("%d", &mark); if (max < mark) max = mark; printf("Max = %dn", max); return 0;輸入一批學生的成績，求最高分(while)#include <stdio.h>int main(void) int mark, max; printf

26、(“Enter marks:"); scanf ("%d", &mark);/* 讀入第一個成績 */ max = mark; /* 假設第一個成績最高分 */ while (mark >= 0) if(max < mark) max = mark ; scanf ("%d", &mark ); ; printf("Max = %dn", max); return 0;2.6 判斷素數(shù)int main(void)int i, m;printf(“Enter a number: ");sc

27、anf ("%d", &m);for (i = 2; i <= m/2; i+) if (m % i = 0) break; if (i > m/2&&m!=1 ) printf("%d is a prime number! n", m); else printf("No!n"); 求100以內(nèi)的全部素數(shù)，每行輸出10個#include <stdio.h>#include <math.h> int main(void) int count, i, m, n; count =

28、0; for (m = 2; m <= 100; m+) n = sqrt(m); for (i = 2; i <= n; i+) if(m % i = 0) break; if(i > n) /* 如果m是素數(shù) */ printf("%6d", m); count+; if (count %10 = 0) /* 每行10個*/ printf(“n”); 2.7 求1! + 2! + . + 100!#include <stdio.h>int main(void)int i, j;double item, sum; sum = 0;for(i

29、= 1; i <= 100; i+) item = 1; for (j = 1; j <= i; j+) item = item * j; sum = sum + item; printf("= %en", sum);第三章：函數(shù)導例：平方根表輸出100以內(nèi)整數(shù)的平方根表，要求每行輸出10個。#include <stdio.h>#include <math.h> /數(shù)學類頭文件int main() int m,n; for (n=0;n<10;n+) printf("%7d", n); /輸出表頭 printf(

30、"n");for(m=0;m<10;m+) printf("%d",m); for (n=0;n<10;n+) printf("%7.4f" ,sqrt(m*10+n); printf("n"); return 0; math.h: 包含與數(shù)學相關的函數(shù) ctype.h：包含與字符處理有關的函數(shù)string.h：包含與字符串處理有關的函數(shù)stdio.h : 包含與輸入輸出有關的函數(shù)stdlib.h : 包含與動態(tài)分配存儲空間和數(shù)值轉(zhuǎn)換有關的函數(shù) process.h:包含與過程控制有關的函數(shù)導例：計算圓柱

31、體積#include <stdio.h>int main( void ) double height, radius, volume;double cylinder (double r, double h); printf ("Enter radius and height: ");scanf ("%lf%lf", &radius, &height);volume = cylinder (radius, height )；printf ("Volume = %.3fn", volume);return 0;

32、double cylinder (double r, double h)double result;result =3.1415926 * r * r * h; return result;例 求兩個數(shù)中的最大值#include <stdio.h>void main( ) int a,b,c,max(int x, int y); scanf(“%d,%d”,&a,&b); c=max(a, b); printf(“Max is %d”,c);int max(int x, int y) int z; if(x>y)z=x; else z=y; return(z)

33、; 4.2.1導例：階乘累加和從鍵盤輸入1個整數(shù)，計算1n的各個數(shù)的階乘的累加和，即1+2！+3！+n!。#include <stdio.h>double fact (int i); /函數(shù)聲明int main(void) int i, n; double sum=0; printf(“Enter 1 integers:”); scanf("%d",&n); for(i = 1; i <=n; i+ ) sum = sum + fact (i); /函數(shù)調(diào)用 printf("1!+%d! = %.0fn", n,sum); re

34、turn 0;double fact (int i) /函數(shù)定義 int j; double result = 1; for (j = 1; j<= i;j+) result = result *j ; return result ; /返回結果導例：判斷素數(shù)的函數(shù)#include <stdio.h>#include <math.h>int main(void) int count, m; int prime (int m); count = 0;for(m = 2; m <= 100; m+) if ( prime(m) != 0) printf(&quo

35、t;%6d", m ); count+; if (count %10 = 0) printf ("n"); printf ("n");prime(int m)int i,n;if(m=1) return 0;n=sqrt(m);for(i=2;i<=n;i+) if(m%i=0) return 0;return 1;輸出5之內(nèi)的數(shù)字金字塔。* 輸出數(shù)字金字塔 */#include <stdio.h>int main (void) void pyramid (int n);pyramid(5); return 0;void py

36、ramid (int n) int i, j;for (i = 1; i <= n; i+) for (j = 1; j <= n-i; j+) printf(" "); for (j = 1; j <= i; j+) printf(" %d ", i); /*前后各有一個空格 */ putchar ('n'); 第四章：數(shù)組5.1.1 導例：如何存儲和操作某班C語言課程的成績#include <stdio.h>#define N 10void main ( )/*定義一維數(shù)組并初始化,長度必須為常量*/in

37、t scoreN=82,76,69,92,53,78,80,88,65,72;int i, t;for(i=0;i<N;i+) /*顯示所有學生的成績*/ printf("%d ",scorei);printf("n");score4=60; /*修改第5名同學的成績*/t=score1; /*互換第2和第7名同學的成績*/score1=score6;score6=t;for(i=0;i<N;i+)/*再次顯示所有學生的成績*/ printf("%d ",scorei);例5-2在數(shù)組中查找一個給定的數(shù)輸入5個整數(shù)，將它們

38、存入數(shù)組a中，再輸入1個數(shù)x，然后在數(shù)組中查找x，如果找到，輸出相應的下標，否則，輸出“Not Found”。#include <stdio.h>int main(void) int i, flag, x; int a5; printf(“Enter 5 integers: "); for(i = 0; i < 5; i+) scanf("%d", &ai); printf(“Enter x: "); scanf("%d", &x); flag = 0; for(i = 0; i < 5; i+

39、) if(ai = x) printf("Index is %dn", i); flag = 1; break; if(flag = 0) printf("Not Foundn"); return 0; 例 5-3 求最小值#include <stdio.h>int main(void) int i, min, n; int a10; printf(“Enter n: "); scanf("%d", &n); printf(“Enter %d integers: ", n); for(i = 0

40、; i < n; i+) scanf("%d", &ai); min = a0; for(i = 1; i < n; i+) if(ai < min) min = ai; printf("min is %d n", min); return 0;求最小值及下標#include <stdio.h>int main(void) int i, index, n; int a10; printf(“Enter n: "); scanf("%d", &n); printf(“Enter %

41、d integers: ", n); for(i = 0; i < n; i+) scanf("%d", &ai); index = 0; for(i = 1; i < n; i+) if(ai < aindex) index = i; printf("min is %dtsub is %dn", aindex, index); return 0;導例5.1.2 選擇法排序利用選擇排序方法將5.1.1導例中全班同學C語言課程成績按照從低到高的順序排列。for( i =0; i < n -1; i +)k = i; /*查找最小元素的下標*/for( j = i +1; j < n; j +)if( aj< ak)k = j; if( k != i)/*將ak和ai交換*/t = ak;ak = ai;ai = t;二分法查找 (程序段)int binarySearch(int a, int n, int x) int low = 0; int high = n - 1; while(lo