Strcmp 与相同字符串进行比较但不进入循环
char* timecompare(){
char time[8];
snprintf(time,8,"%i:%02i",hour(),minute());
return time;
}
char* timefeed = "8:0";
if (strcmp(timecompare(), timefeed) == 0){
Serial.println("hello");
}
当 timecompare() 和 timefeed 都相等时，我将此作为我的代码，它不打印 hello？我这是一个指针问题吗？我不是将 timecompare() 与 timefeed 进行比较，而是将 timecompare() 与“8:0”进行比较，然后循环起作用...这是 timefeed 变量的问题吗？
char* timecompare(){
char time[8];
snprintf(time,8,"%i:%02i",hour(),minute());
return time;
}
char* timefeed = "8:0";
if (strcmp(timecompare(), timefeed) == 0){
Serial.println("hello");
}
I have this as my code when timecompare() and timefeed are both equal it is not printing hello? I this a pointer problem? I instead of comparing timecompare() with timefeed I compare timecompare() with "8:0" then the loop works... Is this a problem with the timefeed variable?
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您将从
timecompare()返回一个堆栈分配变量time。这是非法的，因为堆栈分配的内存仅在声明变量的函数中有效。相反，您需要返回一个堆分配的字符串。你的编译器应该警告你这一点。你可以这样写：
使用完内存后记得
free()内存。You are returning a stack allocated variable,
time, fromtimecompare(). This is illegal since stack allocated memory is only valid in the function in which the variable is declared.Instead you need to return a heap allocated string. Your compiler should be warning you of this. You could write it like this:
Remember to
free()the memory after you are finished with it.您返回超出其范围的局部变量
time。当退出函数timecompare时，返回值不再是有效的指针。另外，将
%02i中的“02”去掉，如果与 8:0 比较，它应该是%i。使用%02i将产生“00”。You return a local variable
timeout of its scope. When you exit the functiontimecompare, the returned value is no longer a valid pointer.Also, remove the "02" from the
%02i, it should be%iif you compare it to 8:0. Using%02iwill yield "00".