c++ - 比较 const char * 和 strcmp

Question

我将 const char * 与字符串进行比较，出于某种原因，它总是成功。

    if (std::strcmp(t->detectColor->name, "ghghjg") != 0) {
        printf("XXXXXXXXXXX\n");
        // check if it was allready a sequencer
        if (std::strcmp(t->className, "IM_SURE_IT_CANT_BE_THIS") != 0) {
          printf("what is going on?\n");

detectColor 名称始终类似于绿色或蓝色，例如，t->className 是“ofxDTangibleBase”。仍然打印

XXXXXXXXXXX
what is going on?

在控制台中。我怎样才能得到一个有效的比较？

Answer 1

根据 cplusplus.com :

Returns an integral value indicating the relationship between the strings: A zero value indicates that both strings are equal. A value greater than zero indicates that the first character that does not match has a greater value in str1 than in str2; And a value less than zero indicates the opposite.

或者由 cppreference.com 表示不同:

Return value

• Negative value if lhs is less than rhs.
• 0​ if lhs is equal to rhs.
• Positive value if lhs is greater than rhs.

因此，在您的代码中，strcmp(t->detectColor->name, "ghghjg") 将返回不同于 0 的内容。因此，将打印“XXXXXXXXXXX”。

你只需要改变:

if (std::strcmp(t->detectColor->name, "ghghjg") != 0)

到

if (std::strcmp(t->detectColor->name, "ghghjg") == 0)

其他对比也一样。