C语言 在 strlen 内部使用短路或电路

Question

result.author = (char *)malloc(sizeof(char)*strlen(temp->author));
strcpy(result.author, temp->author);

我正在做RPC的事情，但这不是问题。在这里，如果 temp 为 NULL，我想分配和复制字符串"UNKNOWN"，如下面的代码所示。

result.author = (char *)malloc(sizeof(char)*strlen(temp->author || "UNKNOWN"));
strcpy(result.author, temp->author || "UNKNOWN");

我怎样才能做到这一点？

Answer 1

result.author = malloc(strlen(temp->author ? temp.author : "UNKNOWN") + 1);
strcpy(result.author, temp->author ? temp.author : "UNKNOWN");

它是以下的简写：

if(temp->author)
{
    result.author = malloc(strlen(temp->author) + 1);
    strcpy(result.author, temp->author);   
}
else
{
    result.author = malloc(strlen("UNKNOWN") + 1);
    strcpy(result.author, "UNKNOWN");   
}