kernighan-and-ritchie

问题 I am stumped by the 1.5.2 question in K&R. I googled for sometime and found out that i have to supply the EOF input after entering the characters. long nc = 0; while (getchar() != EOF) ++nc; printf("%ld\n", nc); return 0; I tried both commnad-D and control-D as EOF inputs but nothing worked. Any Idea how to supply the EOF for mac osx? 回答1: By default, macOS (OS X [formerly Mac OS X]) terminals recognize EOF when Ctrl-D is pressed at the beginning of a line. In detail, the actual operation is

问题 Can somebody please take a look at this and tell me what is wrong. I have 3 errors. 1) error: Conflicting types for getline 2) error: too few arguments to function call, expected 3 have 2 3) error: conflicting types for getline . I'm sure I have overlooked something simple but I cannot find my error. Thank you, here is the code... #include <stdio.h> #define MAXLINE 1000 int getline(char line[], int maxline); /*conflicting types for getline*/ void copy(char to[], char from[]); main(){ int len;

问题 In Kernighan & Ritchie, it says that "all printable characters are positive when though char datatype being signed or unsigned is machine-dependent." Can somebody explain to me the meaning of this line ? My system has signed chars but even with a negative value say of -90, printf does print a character (even though its not a very familiar character). 回答1: ASCII character set defines codepoints from 0x00 to 0x7F . It doesn't matter if they are represented with unsigned or signed byte values

问题 This question already has answers here : Writing a compiler in its own language (12 answers) Closed 6 years ago . This question may stem from a misunderstanding of compilers on my part, but here goes... One can find the following statement in the preface to the first edition of K&R (page xi): The operating system, the C compiler , and essentially all UNIX applications programs (including all of the software used to prepare this book) are written in C. (my emphasis) Here's what I don't

问题 I was looking at an example in K&R 2 (8.6 Example - Listing Directories). It is a stripped down version of Linux command ls or Windows' dir . The example shows an implementation of functions like opendir , readdir . I've tried and typed the code word-by-word but it still doesn't work. All it does is that it prints the a dot (for the current directory) and exits. One interesting thing I found in the code (in the implementation of readdir ) was that it was calling the system calls like open and

问题 I am trying to learn C with The C programming Language by K&R . I am trying to write a the strcat() program using pointers. char *strcat (char *s, char *t){ char *d; d = s; while(*s++); s--; while(*s++ = *t++); return d; } int main () { char *name1; char *name2; name1 = "stack" ; name2 = "overflow"; printf("%s %s\n", name1, name2); printf("strcat out : %s", strcat(name1, name2)); return 0; } But I am getting the ouput as stack overflow Segmentation fault Why is it not working ? Can anybody

问题 I don't fully understand what the following exercise is asking: "Write a program detab that replaces tabs in the input with the proper number of blanks to space to the next tab stop. Assume a fixed set of tab stops, say every n columns. Should n be a variable or a symbolic parameter?" Could someone clarify the bolded part? 回答1: This exercise is asking you to emulate the behavior of tabs by adding the correct amount of spaces, such that the output is still aligned on tab stops. For example :

问题 This exercise is driving me crazy. Sorry if my programming problems seem petty, but I'm a beginner so please bear with me. The exercise asks for the following: Write a program to remove trailing blanks and tabs from each line of input, and to delete entirely blank lines. Can anybody tell me why my code doesn't work? I haven't yet tackled the issue of entirely blank lines, but I can't find any reason why my code won't remove trailing blanks and tabs. Here it is: #include <stdio.h> #define

问题 Is the Most Vexing Parse rooted in the ambiguity about whether or not to use void as the parameter of a function declaration that takes no arguments? As an example, the following code compiles without error, and runs fine, on both the g++ (v7.2.1) and Xcode (Apple LLVM version 7.0.2 (clang-700.1.81)) compilers. #include <iostream> int asdf(void); int asdf(int a) { return a; } int main() { std::cout << asdf(6) << std::endl; //-> 6 return 0; } This goes all the way back to the ANSI-C standard

问题 My question is simply "Why does my code on line 10 and 11 not function properly?" The intended purpose of my code is to do exactly as the original K&R code intended, but to NOT count nc whenever (getchar() == '\n') will you please enlighten me? slightly modified K&R code: /** K&R - 1.5.2 Character Counting **/ #include <stdio.h> /* count characters in input; 1st version */ main(){ long nc; nc = 0; while (getchar() != EOF){ if (getchar() != '\n'){ ++nc; } } printf("%ld\n", nc); } I use 64-bit