help me, factorial in C recursive

This is a discussion on help me, factorial in C recursive within the C Programming forums, part of the General Programming Boards category; can you guys please tell me why this wont do the factorial math!! Code: #include <stdio.h> #include <conio.h> #include <ctype.h> ...

  1. #1
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    Sep 2006
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    help me, factorial in C recursive

    can you guys please tell me why this wont do the factorial math!!

    Code:
    #include <stdio.h>
    #include <conio.h>
    #include <ctype.h>
    
    main()
    {
    int n, total, i;
    total = 1;
    printf("Enter a natural number: ");
    scanf ("%d", &n);
    
    while (n < 0)
    {
    printf ("Error Please Re-Enter Your Natural Number");
    scanf ("%d", &n);
    }
    i = 1;
    
    for (n > 0; i = n; i++)
    {
    total = total * i;
    }
    printf ("%d", total);
    
    fflush(stdin);
    getch();
    return 0;
    }
    Last edited by Dave_Sinkula; 09-23-2006 at 07:55 PM. Reason: Added [code][/code] tags -- learn to use them yourself.

  2. #2
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    The mistake is in the following line:
    Code:
    for (n > 0; i = n; i++)
    Try to think about it: you should make i count from 1 onwards, and stop when it reaches n.

  3. #3
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    fflush(stdin) is undefined.
    getch() is nonportable.
    main() returns int.
    The factorial is not recursively calculated.
    Do you actually know what recursion means?
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  4. #4
    int x = *((int *) NULL); Cactus_Hugger's Avatar
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    Do you actually know what recursion means?
    See my signature.

    In addition to what others have stated (especially the lack of recursion, and the broken for()):
    Indent your code. This will make it so much easier to read - for you and the board.

    For for():
    The first is a statement that occurs at the start of the loop.
    The second part is the condition that must hold true before each iteration.
    The third part is a statement to run after each iteration. So:
    Code:
    for(x = 0; x < 10; ++x)
    Runs for ten iterations. (x starts at zero, the loop runs while x is less than 10, and after each iteration, x is incremented) This is equivalent to:
    Code:
    x = 0;
    while(x < 10)
    {
       statements...
       ++x;
    }
    long time; /* know C? */
    Unprecedented performance: Nothing ever ran this slow before.
    Any sufficiently advanced bug is indistinguishable from a feature.
    Real Programmers confuse Halloween and Christmas, because dec 25 == oct 31.
    The best way to accelerate an IBM is at 9.8 m/s/s.
    recursion (re - cur' - zhun) n. 1. (see recursion)

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