Inserting blank spaces in front of a string? NEED QUICK HELP PLEASE

This is a discussion on Inserting blank spaces in front of a string? NEED QUICK HELP PLEASE within the C Programming forums, part of the General Programming Boards category; Hello all, I'm trying to alter this code for atoi to accept an integer argument, which, if the number is ...

  1. #1
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    Inserting blank spaces in front of a string? NEED QUICK HELP PLEASE

    Hello all, I'm trying to alter this code for atoi to accept an integer argument, which, if the number is larger than the length of the output string, it will insert the difference in spaces in front of the output.

    For instance, if the argument is x= 15
    and the output string is '24835'

    then the final printed output would be 15-5 characters = 10 blank spaces inserted to the left of '24835' so it would print

    24835
    ^^10 blank spaces

    Can anyone please help? Thanks in advance. Also, if someone could please run my code on their comps and verify if my atoi function is correct and gives the correct output please.


    Code:
    #include<stdio.h>
    #include<string.h>
    
    
    /* reverse:     reverse string s in place */
    void reverse(char s[])
    {
            int c,i,j;
    
            for(i = 0,j = strlen(s)-1; i < j; i++,j--)
            {
                    c = s[i];
                    s[i] = s[j];
                    s[j] = c;
            }
    }
    
    /* itoa:  convert n to characters in s */
    void itoa(int n,char s[])
    {
            int i,sign;
    
            if((sign = n) < 0)      /* record sign */
                    n = -n;                 /* make n positive */
    
            i = 0;
    
            do {                                            /* generate
    digits in reverse order */
                    s[i++] = n % 10 + '0';  /* get next digit */
            } while((n /= 10) > 0);         /* delete it */
    
            if(sign < 0)
                    s[i++] = '-';
            s[i] = '\0';
            reverse(s);
    }
    int main()
    {
            char string[50];  /* allocate array space for 50 characters */
            int x;
    
            x = 393;
            itoa(x, string);
            printf("%s\n", string);
            return 0;
    }

  2. #2
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    printf can do what you want:

    Code:
    printf("%10s\n",string);
    Or, the way I believe you want it:

    Code:
    int x = 10;
    printf("%*s\n",x,string);
    It'll add spaces in front of the string if it is less than x characters.
    Your program seems to be working fine.

    Btw if you'd want the itoa() function to store the spaces in your array, you could add the bold code:

    Code:
    void itoa(int n,char s[],int length)
    {
            int i,sign;
    
            if((sign = n) < 0)      /* record sign */
                    n = -n;                 /* make n positive */
    
            i = 0;
    
            do {                                            /* generate
    digits in reverse order */
                    s[i++] = n % 10 + '0';  /* get next digit */
            } while((n /= 10) > 0);         /* delete it */
    
            if(sign < 0)
                    s[i++] = '-';
    
            while(i < length)
              s[i++] = ' ';
    
            s[i] = '\0';
            reverse(s);
    }
    Last edited by Snip; 04-06-2005 at 07:27 AM.

  3. #3
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    wow snip thanks so much! I didn't realize it was that easy...I kept on experimenting with strlength comparisons and even tried to implement a very complicated node pointer scheme...I'm only going on 2 hours sleep so that probably doesn't help much either haha thanks again!

  4. #4
    and the hat of wrongness Salem's Avatar
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    Ditto
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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