C语言10大常见基础算法

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。

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：

Enternumber of terms: 10FibonacciSeries: 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: 200FibonacciSeries: 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: 1232112321is 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<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: 2929is a 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。

11212 312 3 412 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 operatoreither + 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：

Entera positive integer: 34343 + 31345 + 293411 + 233417 + 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 emosewaawesomeprogram

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：