C语言经典算法十例，附源码

素材来源：电子工程专辑

算法是一个程序和软件的灵魂，作为一名优秀的程序员，只有对一些基础的算法有着全面的掌握，才会在设计程序和编写代码的过程中显得得心应手。本文是近百个C语言算法系列的第二篇，包括了经典的Fibonacci数列、简易计算器、回文检查、质数检查等算法。也许他们能在你的毕业设计或者面试中派上用场。

1、计算Fibonacci数列

Fibonacci数列又称斐波那契数列，又称黄金分割数列，指的是这样一个数列：1、1、2、3、5、8、13、21。

C语言实现的代码如下：

/* Displaying Fibonacci sequence up to nth term where n is entered by user. */#include int main(){int count, n, t1=0, t2=1, display=0;printf("Enter number of terms: ");scanf("%d",&n);printf("Fibonacci Series: %d+%d+", t1, t2); /* Displaying first two terms */ count=2; /* count=2 because first two terms are already displayed. */while (count  { display=t1+t2; t1=t2; t2=display; ++count;printf("%d+",display); }return 0;}

结果输出：

Enter number of terms: 10Fibonacci Series: 0+1+1+2+3+5+8+13+21+34+

也可以使用下面的源代码：

/* Displaying Fibonacci series up to certain number entered by user. */
#include int main(){int t1=0, t2=1, display=0, num;printf("Enter an integer: ");scanf("%d",&num);printf("Fibonacci Series: %d+%d+", t1, t2); /* Displaying first two terms */ display=t1+t2;while(display  {printf("%d+",display); t1=t2; t2=display; display=t1+t2; }return 0;}

结果输出：

Enter an integer: 200Fibonacci Series: 0+1+1+2+3+5+8+13+21+34+55+89+144+

2、回文检查

源代码：

/* C program to check whether a number is palindrome or not */
#include int main(){int n, reverse=0, rem,temp;printf("Enter an integer: ");scanf("%d", &n); temp=n;while(temp!=0) { rem=temp%10; reverse=reverse*10+rem; temp/=10; } /* Checking if number entered by user and it's reverse number is equal. */if(reverse==n) printf("%d is a palindrome.",n);elseprintf("%d is not a palindrome.",n);return 0;}

结果输出：

Enter an integer: 1232112321 is a palindrome.

3、质数检查

注：1既不是质数也不是合数。

源代码：

/* C program to check whether a number is prime or not. */
#include int main(){int n, i, flag=0;printf("Enter a positive integer: ");scanf("%d",&n);for(i=2;i<=n/2;++i) {if(n%i==0) { flag=1;break; } }if (flag==0)printf("%d is a prime number.",n);elseprintf("%d is not a prime number.",n);return 0;}

结果输出：

Enter a positive integer: 2929 is a prime number.

4、打印金字塔和三角形

使用 * 建立三角形

** ** * ** * * ** * * * *

源代码：

#include int main(){int i,j,rows;printf("Enter the number of rows: ");scanf("%d",&rows);//微信搜索公众号【C语言中文社区】关注回复C语言，免费领取200G学习资料for(i=1;i<=rows;++i) {for(j=1;j<=i;++j) {printf("* "); }printf("\n"); }return 0;}

如下图所示使用数字打印半金字塔。

11 21 2 31 2 3 41 2 3 4 5

源代码：

#include int main(){int i,j,rows;printf("Enter the number of rows: ");scanf("%d",&rows);for(i=1;i<=rows;++i) {for(j=1;j<=i;++j) {printf("%d ",j); }printf("\n"); }return 0;}

用 * 打印半金字塔

* * * * ** * * ** * ** **

源代码：

#include int main(){int i,j,rows;printf("Enter the number of rows: ");scanf("%d",&rows);for(i=rows;i>=1;--i) {for(j=1;j<=i;++j) {printf("* "); }printf("\n"); }return 0;}

用 * 打印金字塔

 * * * * * * * * ** * * * * * ** * * * * * * * *

源代码：

#include int main(){int i,space,rows,k=0;printf("Enter the number of rows: ");scanf("%d",&rows);for(i=1;i<=rows;++i) {for(space=1;space<=rows-i;++space) {printf(" "); }while(k!=2*i-1) {printf("* "); ++k; } k=0;printf("\n"); }return 0;}

用 * 打印倒金字塔

* * * * * * * * ** * * * * * * * * * * * * * * *

源代码：

#include int main(){int rows,i,j,space;printf("Enter number of rows: ");scanf("%d",&rows);for(i=rows;i>=1;--i) {for(space=0;space printf(" ");for(j=i;j<=2*i-1;++j)printf("* ");for(j=0;j printf("* ");printf("\n"); }return 0;}

5、简单的加减乘除计算器

源代码：

/* Source code to create a simple calculator for addition, subtraction, multiplication and division using switch...case statement in C programming. */
# include int main(){char o;float num1,num2;printf("Enter operator either + or - or * or divide : ");scanf("%c",&o);printf("Enter two operands: ");scanf("%f%f",&num1,&num2);switch(o) {case '+':printf("%.1f + %.1f = %.1f",num1, num2, num1+num2);break;case '-':printf("%.1f - %.1f = %.1f",num1, num2, num1-num2);break;case '*':printf("%.1f * %.1f = %.1f",num1, num2, num1*num2);break;case '/':printf("%.1f / %.1f = %.1f",num1, num2, num1/num2);break;default:/* If operator is other than +, -, * or /, error message is shown */printf("Error! operator is not correct");break; }return 0;}

结果输出：

Enter operator either + or - or * or divide : -Enter two operands: 3.48.43.4 - 8.4 = -5.0

6、检查一个数能不能表示成两个质数之和

源代码：

#include int prime(int n);int main(){int n, i, flag=0;//微信搜索公众号【C语言中文社区】关注回复C语言，免费领取200G学习资料printf("Enter a positive integer: ");scanf("%d",&n);for(i=2; i<=n/2; ++i) {if (prime(i)!=0) {if ( prime(n-i)!=0) {printf("%d = %d + %d\n", n, i, n-i); flag=1; }
 } }if (flag==0)printf("%d can't be expressed as sum of two prime numbers.",n);return 0;}int prime(int n) /* Function to check prime number */{int i, flag=1;for(i=2; i<=n/2; ++i)if(n%i==0) flag=0;return flag;}

结果输出：

Enter a positive integer: 3434 = 3 + 3134 = 5 + 2934 = 11 + 2334 = 17 + 17

7、用递归的方式颠倒字符串

源代码：

/* Example to reverse a sentence entered by user without using strings. */
#include void Reverse();int main(){printf("Enter a sentence: "); Reverse();return 0;}void Reverse(){char c;scanf("%c",&c);if( c != '\n') { Reverse();printf("%c",c); }}

结果输出：

Enter a sentence: margorp emosewaawesome program

8、实现二进制与十进制之间的相互转换

/* C programming source code to convert either binary to decimal or decimal to binary according to data entered by user. */
#include #include int binary_decimal(int n);int decimal_binary(int n);int main(){ int n; char c; printf("Instructions:\n"); printf("1. Enter alphabet 'd' to convert binary to decimal.\n"); printf("2. Enter alphabet 'b' to convert decimal to binary.\n"); scanf("%c",&c); if (c =='d' || c == 'D') { printf("Enter a binary number: "); scanf("%d", &n); printf("%d in binary = %d in decimal", n, binary_decimal(n)); } if (c =='b' || c == 'B') { printf("Enter a decimal number: "); scanf("%d", &n); printf("%d in decimal = %d in binary", n, decimal_binary(n)); } return 0;}
int decimal_binary(int n) /* Function to convert decimal to binary.*/{ int rem, i=1, binary=0; while (n!=0) { rem=n%2; n/=2; binary+=rem*i; i*=10; } return binary;}
int binary_decimal(int n) /* Function to convert binary to decimal.*/{ int decimal=0, i=0, rem; while (n!=0) { rem = n%10; n/=10; decimal += rem*pow(2,i); ++i; } return decimal;}

9、使用多维数组实现两个矩阵的相加

源代码：

#include int main(){int r,c,a[100][100],b[100][100],sum[100][100],i,j;printf("Enter number of rows (between 1 and 100): ");scanf("%d",&r);printf("Enter number of columns (between 1 and 100): ");scanf("%d",&c);printf("\nEnter elements of 1st matrix:\n");
/* Storing elements of first matrix entered by user. */
for(i=0;i for(j=0;j  {printf("Enter element a%d%d: ",i+1,j+1);scanf("%d",&a[i][j]); }
/* Storing elements of second matrix entered by user. */
printf("Enter elements of 2nd matrix:\n");for(i=0;i for(j=0;j  {printf("Enter element a%d%d: ",i+1,j+1);scanf("%d",&b[i][j]); }
/*Adding Two matrices */
for(i=0;i for(j=0;j  sum[i][j]=a[i][j]+b[i][j];
/* Displaying the resultant sum matrix. */
printf("\nSum of two matrix is: \n\n");for(i=0;i for(j=0;j  {printf("%d ",sum[i][j]);if(j==c-1)printf("\n\n"); }
return 0;}

10、矩阵转置

源代码：

#include int main(){ int a[10][10], trans[10][10], r, c, i, j; printf("Enter rows and column of matrix: "); scanf("%d %d", &r, &c);
/* Storing element of matrix entered by user in array a[][]. */ printf("\nEnter elements of matrix:\n"); for(i=0; i  for(j=0; j  { printf("Enter elements a%d%d: ",i+1,j+1); scanf("%d",&a[i][j]); }/* Displaying the matrix a[][] */ printf("\nEntered Matrix: \n"); for(i=0; i  for(j=0; j  { printf("%d ",a[i][j]); if(j==c-1) printf("\n\n"); }
/* Finding transpose of matrix a[][] and storing it in array trans[][]. */ for(i=0; i  for(j=0; j  { trans[j][i]=a[i][j]; }
/* Displaying the transpose,i.e, Displaying array trans[][]. */ printf("\nTranspose of Matrix:\n"); for(i=0; i  for(j=0; j  { printf("%d ",trans[i][j]); if(j==r-1) printf("\n\n"); } return 0;}