{"id":780,"date":"2024-10-19T13:31:15","date_gmt":"2024-10-19T08:01:15","guid":{"rendered":"https:\/\/codexplained.in\/?p=780"},"modified":"2025-11-24T15:37:34","modified_gmt":"2025-11-24T10:07:34","slug":"print-fibonacci-series","status":"publish","type":"post","link":"https:\/\/codexplained.in\/?p=780","title":{"rendered":"Print Fibonacci Series"},"content":{"rendered":"
\n#include <stdio.h>\n\nint main() {\n    int n, firstTerm = 0, secondTerm = 1, nextTerm;\n\n    \/\/ Asking the user for the number of terms\n    printf("Enter the number of terms: ");\n    \n    \/\/ Input validation for non-negative integers\n    if (scanf("%d", &n) != 1 || n < 0) {\n        printf("Invalid input. Please enter a non-negative integer.\\n");\n        return 1;  \/\/ Returning 1 indicates abnormal termination\n    }\n\n    \/\/ Edge cases for Fibonacci sequence\n    if (n == 0) {\n        printf("Fibonacci series: No terms to display.\\n");\n    } else if (n == 1) {\n        printf("Fibonacci series: %d\\n", firstTerm);\n    } else {\n        \/\/ Printing the first two terms\n        printf("Fibonacci series: %d, %d", firstTerm, secondTerm);\n\n        \/\/ Loop to calculate the next terms\n        for (int i = 3; i <= n; ++i) {\n            nextTerm = firstTerm + secondTerm;  \/\/ The next term is the sum of the previous two terms\n            printf(", %d", nextTerm);  \/\/ Printing the next term\n\n            firstTerm = secondTerm;  \/\/ Update firstTerm to the next term\n            secondTerm = nextTerm;  \/\/ Update secondTerm to the next term\n        }\n        printf("\\n");  \/\/ Newline for output formatting\n    }\n\n    return 0;  \/\/ Returning 0 indicates successful termination\n}\n\n<\/pre><\/div>\n\n\n
Explanation:<\/h3>\n\n\n\n
    \n
  1. Including the standard input-output library<\/strong>: We include stdio.h<\/code> to use functions like printf<\/code> and scanf<\/code> for input and output.cCopy code#include <stdio.h><\/code><\/li>\n\n\n\n
  2. Main function<\/strong>: Program execution begins from the main()<\/code> function.cCopy codeint main() { ... }<\/code><\/li>\n\n\n\n
  3. Declaring variables<\/strong>:
    • n<\/code> stores the number of terms the user wants to print in the Fibonacci series.<\/li>
    • t1<\/code> is initialized to 0<\/code>, which represents the first term in the Fibonacci series.<\/li>
    • t2<\/code> is initialized to 1<\/code>, which represents the second term in the Fibonacci series.<\/li>
    • nextTerm<\/code> will store the next number in the sequence as we compute it.<\/li><\/ul>cCopy codeint n, t1 = 0, t2 = 1, nextTerm;<\/code><\/li>\n\n\n\n
    • User input<\/strong>: We prompt the user to input the number of terms using printf<\/code> and then use scanf<\/code> to store this value in the variable n<\/code>.cCopy codeprintf(\"Enter the number of terms: \"); scanf(\"%d\", &n);<\/code><\/li>\n\n\n\n
    • Printing the Fibonacci series<\/strong>:
      • We use a for<\/code> loop that runs n<\/code> times, which means it will print the first n<\/code> terms of the Fibonacci series.<\/li>
      • Inside the loop:
        • We print t1<\/code>, which is the current term in the series.<\/li>
        • We then calculate the next term in the Fibonacci series by adding t1<\/code> and t2<\/code>.<\/li>
        • After calculating nextTerm<\/code>, we update t1<\/code> to t2<\/code> and t2<\/code> to nextTerm<\/code> to move the sequence forward.<\/li><\/ul><\/li>
        • This process is repeated until we print the required number of terms.<\/li><\/ul>cCopy codefor (int i = 1; i <= n; ++i) { printf(\"%d \", t1); nextTerm = t1 + t2; t1 = t2; t2 = nextTerm; }<\/code><\/li>\n\n\n\n
        • Returning 0<\/strong>: The program returns 0<\/code> to indicate that it has executed successfully.cCopy code<\/li>\n<\/ol>\n\n\n\n
          OUTPUT<\/h2>\n\n\n\n
          Enter the number of terms: 10
          Fibonacci Series: 0 1 1 2 3 5 8 13 21 34<\/p>\n\n\n\n
          Summary:<\/h2>\n\n\n\n
          It uses a simple loop and updates the terms of the series iteratively.<\/p>\n\n\n\n
          The Fibonacci series is a sequence where each number is the sum of the two preceding ones, starting with 0<\/code> and 1<\/code>.<\/p>\n\n\n\n
          The program prints the Fibonacci series up to the number of terms specified by the user.<\/p>\n