Iterative Fibonacci in C

Fibonacci without recursion, two variables and a loop.

unsigned long fib(unsigned n) {
    unsigned long a = 0, b = 1;
    while (n--) {
        unsigned long next = a + b;
        a = b;
        b = next;
    }
    return a;
}

Keywords and builtins used here

• fib
• long
• return
• unsigned
• while

The run, in numbers

Lines

9

Characters to type

132

Tokens

46

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 31 seconds.

Type this snippet

Step 5 of 7 in Functions, step 19 of 35 in Language basics.

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Iterative Fibonacci in other languages

• Go
• Rust