c - 在 strlen 中使用短路或电路？

Question

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

strcpy(result.author, temp->author);

我正在做一个 RPC 的事情，但这不是问题所在。如果 temp 像下面的代码一样为 NULL，我想在这里分配和复制字符串“UNKNOWN”。

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 :

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");   
}