的fscanf求助：如何检查格式化 [英] fscanf help: how to check for formatting

问题描述

所以当前功能应该查看存储任何东西二镑符号之间（＃ABC＃应该还给ABC），但如果我想错误检查，看看是否有井号丢失，或者英镑符号之间没有什么，或者说，在这两个井号之间的字符串的长度超过一定数目的字符时，我用fscanf函数来做到这一点？

So the current function is supposed to see anything stored between two pound signs (#abc# should give back abc), but if I want to error check to see if there's a pound sign missing, or there's nothing between the pound signs, or that the length of the string in between the two pound signs is greater than a certain number of characters, do I use the fscanf function to do that?

这里是的fscanf code样子：

Here's what the fscanf code looks like:

if (fscanf(fp, " %c%[^#]%c", &start, buffer, &end) == 3) {
    return strdup(buffer);      
} else { 
    return NULL; 

}

推荐答案

如果您需要处理零字符的情况下，则可能是的fscanf（）不是正确的工具。有一个合理的说法，的fscanf（）很少有正确的工具;你会使用与fgets（）和的sscanf（）。

If you need to deal with the zero-characters case, then probably fscanf() is not the right tool. There's a reasonable argument that fscanf() is seldom the correct tool; you'd do better with fgets() and sscanf().

在这种情况下，我会收集行，直到有一个不为空（因为那是在的fscanf（）一样），然后搜索＃符号与和strchr（）：

In this case, I'd collect lines until there's one that's not blank (since that's what the fscanf() does), and then search for the # symbols with strchr():

char line[4096];
while (fgets(line, sizeof(line), fp) != 0)
{
    if (strspn(line, " \t\n") == strlen(line))
        continue;
    char *hash1 = strchr(line, '#');
    if (hash1 == 0)
        ...error no hashes...
    else
    {
        char *hash2 = strchr(hash1+1, '#');
        if (hash2 == 0)
            ...second hash is missing...
        if (hash2 - hash1 > MAX_PERMITTED_STRING_LEN)
            ...too long a string...
        *hash2 = '\0';
        char *res = strdup(hash1);
    }
}

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