我正在尝试读取一个用户输入字符串，该字符串将仅记录用户输入键而不记录""。
因此，分隔用户输入的命令和参数，例如"mkdir hello"（"mkdir" = 命令，"hello" = 参数）返回参数（"hello"）。
有没有办法有效地删除""？
另外，你如何空终止字符串？
int main(void) {
char directoryName[129] = "";
printf("nProgram Start... nn");
// getting user input string
// and splitting command and argument
char inputString[129];
char delimiter[] = " ";
char *line;
char *arg;
struct tree_node *root = make_tree_node("root ");
//struct tree_node *cwd = make_tree_node("root ");
struct tree_node *cwd = root;
printf("/%s >", directoryName);
while (fgets(inputString, 128, stdin)) {
// char * before strsep, set pointer to be original checkString
// original checkString
// then free memory
// gets argument and stores as arg
line = malloc(sizeof(char) * strlen(inputString));
strcpy(line, inputString);
arg = strsep(&line, delimiter);
arg = strsep(&line, delimiter);
printf("your argument: %sn", arg);
printf("/%s >", directoryName);
}
整个代码：
#include <stdio.h> /* For fgets(), fprintf() and printf() */
#include <stdlib.h> /* For EXIT_FAILURE */
#include <ctype.h> /* For isspace() */
#include <string.h>
#include <stddef.h>
// COMMANDS
char exitProgram[] = "exit";
char listDirectory[] = "ls";
char commandDirectory[] = "cd";
char makeDirectory[] = "mkdir";
char removeDirectory[] = "rmdir";
// holds a string buffer of length 128
// a pointer to its parent
// a pointer to the first node of the list of children
typedef struct tree_node {
char string_buffer[128];
struct tree_node *parent;
struct list_node *first_child; // first node of list of children?
} tree_node;
// pointer to tree node
// pointer to next item in the list
typedef struct list_node {
struct tree_node *tree;
struct list_node *next;
} list_node;
// allocates the right amount of space for a tree node
// sets the pointers to NULL
// initialises the string buffer with the given name
// returns a pointer to the tree node
struct tree_node *make_tree_node(char *name) {
tree_node *tree = malloc(sizeof(*tree));
tree -> parent = NULL;
tree -> first_child = NULL;
strcpy(tree -> string_buffer, name);
return tree;
}
// allocates a new list node
// assigns the fields for the tree node it references and the next list node
// returns a pointer to the new list node
struct list_node *make_list_node(struct tree_node *v, struct list_node *next) {
list_node *instance = malloc(sizeof(*instance));
instance -> tree = v;
instance -> next = next;
return instance;
}
// checks whether directory named arg already exists in current working directory
// creates the directory if it does not exist
// if arg is NULL, the function should print an error message
void do_mkdir(struct tree_node *cwd, char *arg) {
printf("Making Directory with name %s n", arg);
// check if directory exists
struct list_node *subDir = cwd->first_child;
while (subDir != NULL) {
if (strcmp(subDir->tree->string_buffer, arg) == 0) {
printf("Directory with that name exists. Please provide another name.n");
return;
}
subDir = subDir->next;
}
// adding new directory
struct tree_node *newSubDir = make_tree_node(arg);
newSubDir->parent = cwd;
struct list_node *newListNode = make_list_node(newSubDir, NULL);
// putting new node in alphabetical order
struct list_node *prev = NULL;
if (subDir == NULL) {
newListNode->next = cwd->first_child;
cwd->first_child = newListNode;
} else {
while (subDir != NULL) {
// TODO: use case insensitive compare
if (strcmp(arg, subDir->tree->string_buffer) > 0) {
// inserting in front
newListNode->next = subDir->next;
prev->next = newListNode;
break;
}
prev = subDir;
subDir = subDir->next;
}
if (subDir == NULL) {
subDir->next = newListNode;
}
}
printf("Directory added: %s", arg);
}
// prints all children of the directory cwd (not recursively)
void do_ls(struct tree_node *cwd) {
printf("Listing Directories...n");
struct list_node *subDir = cwd -> first_child;
while (subDir != NULL) {
printf("%s", subDir ->tree -> string_buffer);
subDir = subDir->next;
}
}
// *checks whether cwd has a subdirectory named arg
// *if yes, the function returns the corresponding tree node (and become new working directory)
// *if no, prints an error message
// *handle cd and cd ..
struct tree_node *do_cd(struct tree_node *cwd, struct tree_node *root, char *arg) {
// checks if cwd has a subdirectory named arg
struct list_node *subDir = cwd -> first_child;
while (subDir != NULL) {
if (strcmp(subDir->tree->string_buffer, arg) == 0) {
printf("Subdirectory exists: Entering!n");
subDir->tree = cwd;
printf("Making subdirectory current working directory: name = %sn", arg);
printf("Returning current working directory: %s.n", arg);
return cwd;
}
subDir = subDir->next;
}
printf("Directory does not exist!n");
return NULL;
}
// *prints the prompt (e.g. /bar/baz/ >) in every iteration of the main loop
// *show all directories on the path in correct order
//void show_prompt(struct tree_node *cwd) {
// while(cwd != NULL) {
// printf(cwd->string_buffer);
//show all directories on the path in correct order.
// }
// printf("/");
//}
// *removes a node child from its parent node dir
// *take care to correctly support corner cases like the child being the only one
// *all memory occupied by the child should be freed
//void remove_child(struct tree_node *dir, struct tree_node *child) {
// if (dir == NULL) {
// printf("Current directory is empty!");
// }
// else if (dir -> child != NULL) {
// free(child);
// }
//}
// implement rmdir (follow same pattern as previous exercise)
// *if the specified directory is not empty, rmdir should fail with an error message
//void do_rmdir(struct tree_node *cwd, char *arg) {
// if(cwd != NULL) {
// printf("Specified directory is not empty!");
// } else {
// free(cwd);
// }
//}
int main(void) {
char directoryName[129] = "";
printf("nProgram Start... nn");
// getting user input string
// and splitting command and argument
char inputString[129];
char delimiter[] = " ";
char *line;
char *arg;
struct tree_node *root = make_tree_node("root ");
//struct tree_node *cwd = make_tree_node("root ");
struct tree_node *cwd = root;
printf("/%s >", directoryName);
while (fgets(inputString, 128, stdin)) {
// char * before strsep, set pointer to be original checkString
// original checkString
// then free memory
// gets argument and stores as arg
line = malloc(strlen(inputString) + 1);
strcpy(line, inputString);
arg = strsep(&line, delimiter);
arg = strsep(&line, delimiter);
printf("your argument: %sn", arg);
printf("/%s >", directoryName);
//printf("userInput:%s", inputString);
if(strncmp(inputString, "exit", 4) == 0) {
printf("Breaking...n");
break;
}
////////////////////////////// HANDLING LS ////////////////////////////
else if(strncmp(inputString, "ls ", 3) == 0) {
printf("The ls command should be used without arguments.n");
}
else if(strncmp(inputString, "ls", 2) == 0) {
do_ls(cwd);
printf("/%s >", directoryName);
}
////////////////////////////// HANDING CD /////////////////////////////
else if(strncmp(inputString, "cd ..", 5) == 0) {
printf("Returning to previous directory.n");
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "cd .", 4) == 0) {
printf("Returning to current directory.n");
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "cd ", 3) == 0) {
do_cd(cwd, root, arg);
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "cd", 2) == 0) {
printf("Returning to root directory.n");
printf("/%s >", directoryName);
}
/////////////////////////// HANDLING MKDIR /////////////////////////////
else if(strncmp(inputString, "mkdir ", 7) == 0) {
printf("Please specify directory name that is not NULL: mkdir directoryNamen");
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "mkdir ", 6) == 0) {
do_mkdir(cwd, arg);
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "mkdir", 5) == 0) {
printf("Please specify directory name: mkdir directoryNamen");
printf("/%s >", directoryName);
}
//////////////////////// HANDLING RMDIR /////////////////////////////////
else if(strncmp(inputString, "rmdir ", 7) == 0) {
printf("Please specify directory name that is not NULL: rmdir directoryNamen");
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "rmdir ", 6) == 0) {
printf("Removing Directory with name...n");
//
printf("/%s >", directoryName);
}
else if(strncmp(inputString, "rmdir", 5) == 0) {
printf("Please specify directory name: rmdir directoryNamen");
printf("/%s >", directoryName);
}
else {
printf("Unrecognised input: Please try again.n");
printf("/%s >", directoryName);
}
}
printf("nProgram Quit... nn");
return 0;
}
您可以使用：
while (fgets(inputString, 128, stdin)) {
inputString[strlen(inputString)-1] = ' ';
...
我用我的更改尝试您的程序，输出示例：
Program Start...
/ >mkdir hello
your argument: hello
/ >Making Directory with name hello
Directory added: hello/ >