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    <p>i think there is some problem with global scope and local scopes in this code below. if anyone please help me, why this code is not working!! this is a program to find 25th magical number.magical number means it has no prime factor except 2,3,5. i have started from 16 which is 12th magical number. and then checking the numbers if they are divisible with any prime number from 7. so i list the prime numbers in a global array. and check the numbers with those prime in the arrays. and if this checking is complete, the program tries to find next prime number by using the next_prime function and list them into the global array. but i am getting wrong result. it is always giving the result input+=4 which is not expected. </p> <pre><code>/*a program to find out 25th magical number. magical number means it has no prime factor except 2,3,5*/ #include&lt;stdio.h&gt; #include&lt;math.h&gt; double primes[10000]={2,3,5}; int serial=3; double next_prime(double f)//function, when called, returns the next prime number { int j=0,loop_breaker=0; int count; while(j==0){ for(count=1;primes[count]&lt;sqrt(f)+1 &amp;&amp;count&lt;serial;count++){ if(fmod(f,primes[count])==0){ f+=2; loop_breaker=1; break; } } if(loop_breaker==0){ primes[serial]=f; serial++; j=1; } } return f; } int main() { double f=7,prime_divisor,magic_serial=12,magic_number=16; int c,loop_breaker,is_magic; prime_divisor=next_prime(f); f+=2;//this line always comes after the previous line so that everytime the value of f gets changed while(magic_serial!=25){ is_magic=0; loop_breaker=0; for(c=3;c&lt;serial;c++){ if(fmod(magic_number,primes[c])==0){ loop_breaker=1; break; } } if(loop_breaker==0){ while(prime_divisor&lt;sqrt(magic_number)+1){ prime_divisor=next_prime(f); f+=2; if(fmod(magic_number,prime_divisor)==0){ is_magic=1; break; } } } if(is_magic==0){ magic_serial++; } magic_number++; } printf("%lf",magic_number); return 0; } </code></pre>
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    1. COWhat's your expected scoping for `double f`?
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    2. COit's in the main function
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    3. CORemember that C arrays start at index 0, not index 1...
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