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<stdio.h>intmain(){intcount, 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<n) { display=t1+t2; t1=t2; t2=display; ++count;printf("%d+",display); }return0; }

结果输出：

Enter numberofterms: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<stdio.h>intmain(){intt1=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<num) {printf("%d+",display); t1=t2; t2=display; display=t1+t2; }return0; }

结果输出：

Enteran 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<stdio.h>intmain(){intn, 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);return0; }

结果输出：

Enteran integer:1232112321isa 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<stdio.h>intmain(){intn, 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);return0; }

结果输出：

Entera positive integer:2929isa prime number.

4、打印金字塔和三角形

使用 * 建立三角形

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

源代码：

#include<stdio.h>intmain(){inti,j,rows;printf("Enter the number of rows: ");scanf("%d",&rows);for(i=1;i<=rows;++i) {for(j=1;j<=i;++j) {printf("* "); }printf("\n"); }return0; }

如下图所示使用数字打印半金字塔。

1 1 2 1 2 3 1 2 3 4 1 2 3 4 5

源代码：

#include<stdio.h>intmain(){inti,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"); }return0; }

用 * 打印半金字塔

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

源代码：

#include<stdio.h>intmain(){inti,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"); }return0; }

用 * 打印金字塔

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

源代码：

#include<stdio.h>intmain(){inti,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"); }return0; }

用 * 打印倒金字塔

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

源代码：

#include<stdio.h>intmain(){introws,i,j,space;printf("Enter number of rows: ");scanf("%d",&rows);for(i=rows;i>=1;--i) {for(space=0;space<rows-i;++space)printf("  ");for(j=i;j<=2*i-1;++j)printf("* ");for(j=0;j<i-1;++j)printf("* ");printf("\n"); }return0; }

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 <stdio.h>intmain(){charo;floatnum1,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; }return0; }

结果输出：

Enter operator either +or-or*ordivide : - 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<stdio.h>intprime(intn);intmain(){intn, i, flag=0;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);return0; }intprime(intn)     /* Function to check prime number */{inti, flag=1;for(i=2; i<=n/2; ++i)if(n%i==0) flag=0;returnflag; }

结果输出：

Enter a positive integer: 34 34 = 3 + 31 34 = 5 + 29 34 = 11 + 23 34 = 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<stdio.h>voidReverse();intmain(){printf("Enter a sentence: "); Reverse();return0; }voidReverse(){charc;scanf("%c",&c);if( c !='\n') { Reverse();printf("%c",c); } }

结果输出：

Entera sentence: margorp emosewa awesome 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<stdio.h>#include<math.h>intbinary_decimal(intn);intdecimal_binary(intn);intmain(){intn;charc;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)); }return0; }intdecimal_binary(intn) /* Function to convert decimal to binary.*/{intrem, i=1, binary=0;while(n!=0) { rem=n%2; n/=2; binary+=rem*i; i*=10; }returnbinary; }intbinary_decimal(intn)/* Function to convert binary to decimal.*/{intdecimal=0, i=0, rem;while(n!=0) { rem = n%10; n/=10; decimal += rem*pow(2,i); ++i; }returndecimal; }

结果输出：

9、使用多维数组实现两个矩阵的相加

源代码：

#include<stdio.h>intmain(){intr,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<r;++i)for(j=0;j<c;++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<r;++i)for(j=0;j<c;++j) {printf("Enter element a%d%d: ",i+1,j+1);scanf("%d",&b[i][j]); }/*Adding Two matrices */for(i=0;i<r;++i)for(j=0;j<c;++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<r;++i)for(j=0;j<c;++j) {printf("%d   ",sum[i][j]);if(j==c-1)printf("\n\n"); }return0; }

结果输出：

10、矩阵转置

源代码：

#include<stdio.h>intmain(){inta[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<r; ++i)for(j=0; j<c; ++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<r; ++i)for(j=0; j<c; ++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<r; ++i)for(j=0; j<c; ++j) { trans[j][i]=a[i][j]; }/* Displaying the transpose,i.e, Displaying array trans[][]. */printf("\nTranspose of Matrix:\n");for(i=0; i<c; ++i)for(j=0; j<r; ++j) {printf("%d  ",trans[i][j]);if(j==r-1)printf("\n\n"); }return0; }

结果输出：