我现在正在上C编程课程,并且正在制作类似于bash的shell。现在,我正在实施管道。因此,我需要strndup
管道命令在解析时不修改原始管道命令。最后,我尝试free
指向malloc
的指针,但是我的程序无法正常工作。有人可以告诉我我做错了什么吗?下面是解析器的while循环的代码:
while (pipeSeparatedCommand != NULL) {
char *duplicateCmdForPiping = strndup(pipeSeparatedCommand,strlen(pipeSeparatedCommand)); // duplicates command
pipeSeparatedCommand = strtok(NULL,"|"); // starts at the NULL Character that was tokenized
char *token = strtok(duplicateCmdForPiping," "); // finds the first space in the command,tokenizes the arguments by this space
int index = 0; // counts the number of commands and arguments
while (token != NULL) {
if ((input != NULL) || (output != NULL)) { // advances to the next argument if input or output is found (does not include them in args)
token = strtok(NULL," ");
continue;
}
commandArgsCount[index]++;
commandArray[numberOfPipes][index] = token; // sets the argument index equal to the address of token (containing the token)
token = strtok(NULL," "); // token will search for the next delimiter from the last delimiter end spot
index++;
}
commandArray[numberOfPipes + 1][index] = NULL; // prevents the args array from collecting garbage in memory.
if (pipeSeparatedCommand != NULL) // catches the zero case
numberOfPipes++; // this begins at zero,increments if more pipes need to be added
free(duplicateCmdForPiping);
duplicateCmdForPiping = NULL;
}