我在code review发布了我的代码并得到了我没有进行错误检查的答案。 AFAIK我可以通过多种方式进行错误检查：
perror使用或类似，我有时会这样做，但我还没有学到它有更多方法可以做到这一点或建议的某种特定方式吗？使用perror和断言是好还是坏？代码位于my github，main循环如下所示：
int main(int argc, char *argv[]) {
bool donotrun = false;
struct sigaction new_action, old_action;
hashtable_t *hashtable = ht_create(65536);
/* Set up the structure to specify the new action. */
new_action.sa_handler = termination_handler;
sigemptyset(&new_action.sa_mask);
new_action.sa_flags = 0;
sigaction(SIGINT, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGINT, &new_action, NULL);
sigaction(SIGHUP, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGHUP, &new_action, NULL);
sigaction(SIGTERM, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGTERM, &new_action, NULL);
void *pParser;
char *c;
int index = 0;
int i;
char *cvalue = NULL;
const char *commandFile = "";
bool quietFlag;
while (1) {
index = 0;
i = getopt_long(argc, argv, "pc:vh",
options, &index);
if (i == -1)
break;
switch (i) {
case 'p': {
exit(EXIT_SUCCESS);
}
case 'v': {
printf("sh OpenShell version 0.1(a)\n");
printf("Version: %s\n", VERSION);
exit(EXIT_SUCCESS);
}
case 'h': {
usage();
exit(EXIT_SUCCESS);
}
case 'c': {
cvalue = optarg;
command(cvalue, hashtable);
exit(EXIT_SUCCESS);
}
case 'f':
/*
* Execute commands from file.
* This is used for osh script files.
* The quiet flag is also set.
*/
if ((argc != 1) || commandFile)
usage();
quietFlag = true;
argc--;
break;
case '?':
if (optopt == 'c')
fprintf(stderr, "Option -%c requires an argument.\n", optopt);
else if (isprint (optopt))
fprintf(stderr, "Unknown option `-%c'.\n", optopt);
else
fprintf(stderr,
"Unknown option character `\\x%x'.\n",
optopt);
default: {
return 1;
}
}
}
getPath();
pParser = (void *) ParseAlloc(malloc);
char *copy = "";
for (; ;) {
bool scanning = true;
bool calc = true;
while (scanning) {
char *line = NULL;
line = readline("$ ");
if (line == NULL) {
/* No more lines, so exit the loop. */
break;
}
if (line)
copy = strdup(line);
if (line && !strstr(line, "for") && !strstr(line, "==") && !strstr(line, "if") && strstr(line, "=")) {
donotrun = true;
char str[128];
char *ptr;
strcpy(str, line);
strtok_r (str, "=", &ptr);
ht_set(hashtable, str, ptr);
}
if (!scanning)
break;
if (!isatty(fileno(stdin))) {
*argv++;
readFile(*argv++, hashtable);
free(line);
exit(0);
}
else {
if (!donotrun) {
line = str_replace(line, " | ", "|");
line = str_replace(line, " |", "|");
command(line, hashtable);
}
donotrun = false;
add_history(copy);
}
free(copy);
}
}
// ParseFree(pParser, free);FIXME: where should this go?
return 0;
}
然后我断言我必须在开发期间注释掉，现在我不确定断言应该是什么。
/* Returns a struct that has the number of "chunks" the list of chunks.
* Splits the command by char | and then by whitespace and return a list of struct pointers
*/
struct str_list *list_split(const char *a_str, char *a_delim) {
char **result = 0;
size_t count = 0;
char *tmp = (char *) a_str;
char *ctmp;
char *token = "";
char *last_comma = 0;
char *tmp2 = (char *) a_str; /* TODO: This variable can reuse tmp */
//char *delim[2];
//delim[0] = a_delim;
struct str_list *chunks = NULL;
/* Count how many elements will be extracted. */
while (*tmp) {
if (*a_delim == *tmp) {
count++;
last_comma = tmp;
}
tmp++;
}
/* Add space for trailing token. */
count += last_comma < (a_str + strlen(a_str) - 1);
count++;
result = alloc_argv(count);
char **tmpresult = alloc_argv(count);
chunks = malloc(count * sizeof *chunks);
if (result == NULL) {
printf("Error allocating memory!\n");
return chunks;;
}
if (result) {
size_t idx = 0;
token = strtok((char *) strdup(a_str), "|");
int a = 0;
while (token) {
// assert(idx < count); Why must I turn off assertions?
tmpresult[a] = strdup(token);
a++;
ctmp = strdup(token);
*(result + idx++) = ctmp; /* memory leak! how to free() */;
token = strtok(0, a_delim);
}
// assert(idx == count - 1);
*(result + idx) = 0;
}
chunks->argv = alloc_argv(BUFFER_SIZE);//malloc(chunks->size * sizeof(char *) * 1);
int i = 0;
chunks = tokenize(&i, chunks, result, count, tmp2);
chunks->pipes = i; /* important! to get this right */
free(ctmp);
return expand_shell(tmpresult, chunks);
}
答案 0 :(得分：4)
据我所知，断言应仅在开发和测试期间使用。断言实际上是一个宏。在构建调试配置时，它会执行检查并退出（如果为false）。当您处于发布配置时，它什么都不做。因此，断言应该用于检查编程错误。
http://www.cplusplus.com/reference/cassert/assert/
你不能用assert做的是检查运行时错误，这意味着在程序执行期间由于环境或用户输入而发生的错误，例如程序无法打开或写入文件，用户在需要编号时输入字符串，无法建立网络连接等。您希望在调试和释放模式下都能进行这些检查。
我认为你提到的另外两个错误检查方法，perror和检查返回值，总是在一起。通常会检查函数的返回值，然后打印消息（带有perror或其他函数），然后执行错误恢复或退出。 perror本身只是打印一条消息，程序会继续，除非你做其他事情。
http://www.cplusplus.com/reference/cstdio/perror/
通常应该检查外部函数调用的返回值，并检查程序的所有输入是否正确。大多数库函数都可能失败，包括malloc或printf，但根据您的偏执程度，它只能检查最有可能导致问题的文件（文件，网络，库或设备初始化等），具体取决于您的应用