Thread: K&R array program learning

Indentation fixed. Actual fixes noted with // comments. The main issue was c <= '0' when it needed to be c >= '0'.

The program is generating a histogram.

Code:

#include<stdio.h>
int main()
{
    int c,i,nwhite,nother;
    int ndigit[10];

    nwhite = nother = 0;
    for(i = 0; i < 10; ++i)
        ndigit[i] = 0;                                  // 0

    while((c = getchar()) != EOF)
         if(c >= '0' && c <= '9')                       // >= 
             ++ndigit[c- '0'];
         else if (c == ' ' || c == '\n' || c == '\t')   // ' '
             ++nwhite;
         else
             ++nother;
    printf("digits =");
    for(i = 0; i < 10; i++)                             
    // spaces on the next two lines
        printf(" %d", ndigit[i]);
    printf(", white space = %d, other = %d\n", nwhite ,nother);
    return(0);                                          // return
}

Input, if one line:

Code:

1234567890|asdf

You might also want to look up functions in the standard header <ctype.h>. There are facilities there like isdigit() to test if a character is a digit, isspace() to test if a character is whitespace, isalpha() to test for alphabetic characters, and more.

Note that those standard functions also work with internationalisation (for example, the notion of what is an alphabetic character varies with natural language). Also, there are more whitespace characters than just the three you are testing for.