ccpalettes/the-c-programming-language-second-edition-solutions

Solutions for all exercises in the book "The C Programming Language - Second Edition"(referred to as K&R, after its authors' initials) by Brian W. Kernighan and Dennis M. Ritchie.

the-c-programming-language-second-edition-solutions

Solutions for all exercises in the book "The C Programming Language - Second Edition"(referred to as K&R, after its authors' initials) by Brian W. Kernighan and Dennis M. Ritchie.

the-c-programming-language-second-edition-solutions's Issues

2-4 does not terminate

I find the program does not terminate on Windows.
But the following code works:

void squeeze(char s1[], char s2[])
{
    int i=0;//s1 ptr
    char tmp[MAXLINE];
    int k=0;//tmp ptr
    while(s1[i]!='\0'){
        int find_flag = 0;
        int j=0;//s2 ptr
        while(s2[j]!='\0'){
            if(s1[i]==s2[j]){//match!
                find_flag=1;
                break;
            }
            j++;
        }
        if(find_flag==0){
            tmp[k]=s1[i];
            k++;
        }
        i++;
    }
    tmp[k]='\0';
    for(int ii=0;ii<k+1;ii++)
        s1[ii]=tmp[ii];
}

No comments in source code, not easily understandable

write comments !!

Longest-line program (1.17)

The exercise explicitly mentions that you have to revise the main routine of the program, yet the solution has revised the get_line function. https://github.com/ccpalettes/the-c-programming-language-second-edition-solutions/blob/master/Chapter1/Exercise%201-16/longest_line.c

That's why I did it like so:

main()
{
    int len;            /* current line length */
    int counter;        /* counts how many times len has reached MAXLINE - 1 */
    int max;            /* maximum length seen so far */
    char firstline[MAXLINE];/* first part of the line to be printed */
    char line[MAXLINE];     /* current input line */
    char longest[MAXLINE];  /* longest line saved here */

    counter = max = 0;
    while ((len = fetchline(line, MAXLINE)) > 0) {
        while (len == MAXLINE - 1 && line[MAXLINE - 1] != '\n') {
            if (counter == 0)
                copy(firstline, line);
            ++counter;
            len = fetchline(line, MAXLINE);
        }
        len = counter * (MAXLINE - 1) + len;
        if (len > max) {
            max = len;
            if (counter > 0)
                copy(longest, firstline);
            else
                copy(longest, line);
        }
        counter = 0;
    }
    if (max > 0)    /* there was a line */
        printf("%s\n%d\n", longest, max);
    return 0;
}

Before this exercise is presented, the authors even suggest this solution ("By testing the length and the last character returned, main can determine whether the line was to long, and then cope as it wishes."). That is why I believe this is actually the correct solution.

exercise2-3 should add 10 at 53 and 55 line

and its retract is not correct

Excersise 4-13 broken for even length inputs.

Any input with even length will not properly reverse the middle two characters.

For example, inputting 12 will output 12, inputting 1234 will output 4231, inputting 123456 will output 653421, etc.

Odd length inputs work as intended.

exercise 1.12 does not ignore first whitespace

$ printf '  word1 word2 word3\tword4\nword5 \n word6\tword7\n' | ./test # your code

word1
word2
word3
word4
word5
word6
word7

I'm using something like this:

#include <stdio.h>

int
main()
{
        int z;

        word = 0;

        while ((z = getchar()) != EOF) {
                if (z == ' ' || z == '\t' || z == '\n') {
                        if (word) {
                                printf("\n");
                                word = 0;
                        } else
                                continue;
                } else {
                        putchar(z);
                        word = 1;
                }
        }
        return(0);
}

$ printf '  word1 word2 word3\tword4\nword5 \n word6\tword7\n' | ./main
word1
word2
word3
word4
word5
word6
word7