Algorithms are the soul of programs and software. As an excellent programmer, only by having a comprehensive grasp of some basic algorithms can you become handy in the process of designing programs and writing code. This article is the second in nearly 100 C-language algorithm series, including classic Fibonacci sequences, simple calculators, palindrome inspection, prime number inspection and other algorithms. Maybe they can come in handy in your graduation project or interview.
1. Calculate the Fibonacci sequence
The Fibonacci sequence is also called the Fibonacci sequence, also known as the golden section sequence, which refers to a sequence: 1, 1, 2, 3, 5, 8, 13, 21.
The code implemented in C language is as follows:
/* 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<n)
{
display=t1+t2;
t1=t2;
t2=display;
++count;
printf("%d+",display);
}
return 0;
}
Results output:
Enter number of terms: 10 Fibonacci Series: 0+1+1+2+3+5+8+13+21+34+
You can also use the following source code:
/* 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<num)
{
printf("%d+",display);
t1=t2;
t2=display;
display=t1+t2;
}
return 0;
}
Results output:
Enter an integer: 200
Fibonacci Series: 0+1+1+2+3+5+8+13+21+34+55+89+144+
2. Palindrome check
source code:
/* 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);
else
printf("%d is not a palindrome.",n);
return 0;
}
Results output:
Enter an integer: 12321
12321 is a palindrome.
3. Prime number check
Note: 1 is neither a prime nor a composite number.
source code:
/* 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);
else
printf("%d is not a prime number.",n);
return 0;
}
Results output:
Enter a positive integer: 29
29 is a prime number.
4. Print pyramids and triangles
Use * to create a triangle
*
* *
* * *
* * * *
* * * * *
source code:
#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("* ");
}
printf("\n");
}
return 0;
}
Print the semi-pyramid using numbers as shown in the figure below.
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
source code:
#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;
}
Print semi-pyramid with *
* * * * *
* * * *
* * *
* *
*
source code:
#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;
}
Print pyramids with *
*
* * *
* * * * *
* * * * * * *
* * * * * * * * *
source code:
#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;
}
Print inverted pyramid with *
* * * * * * * * *
* * * * * * *
* * * * *
* * *
*
source code:
#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<rows-i;++space)
printf(" ");
for(j=i;j<=2*i-1;++j)
printf("* ");
for(j=0;j<i-1;++j)
printf("* ");
printf("\n");
}
return 0;
}
5. Simple addition, subtraction, multiplication and division calculator
source code:
/* 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;
}
Results output:
Enter operator either + or - or * or divide : -
Enter two operands: 3.4
8.4
3.4 - 8.4 = -5.0
6. Check whether a number can be represented as the sum of two prime numbers
source code:
#include <>
int prime(int n);
int main()
{
int n, 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);
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;
}
Results output:
Enter a positive integer: 34
34 = 3 + 31
34 = 5 + 29
34 = 11 + 23
34 = 17 + 17
7. Reverse strings in recursive way
source code:
/* 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);
}
}
Results output:
Enter a sentence: margorp emosewa
awesome program
8. Implement mutual conversion between binary and decimal
/* 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;
}
Results output:
9. Use multi-dimensional array to implement the addition of two matrices
source code:
#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<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");
}
return 0;
}
10. Matrix Transposition
source code:
#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<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,, 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");
}
return 0;
}
Summarize
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