iphone - 主要在IOS中是如何工作的

Question

我在做我的 IOS 项目时遇到了一个疑问，为了我们的测试目的，我们在 main... 中写了一段这样的代码......

printf("start\n");
FILE *fp = fopen("/Users/gui_test/Desktop/ritun/hello_test/hello_test/expt.txt", "a + b");

int a = 5, b = 5;
int c = a + b;

fprintf(fp, "%d\t", c);
fflush(fp);

fclose(fp);

printf("end \n");

我已经在 main 中注释掉以下行以测试文件写入。

return UIApplicationMain(argc, argv, nil, NSStringFromClass([ofi_video_monetAppDelegate class]));

答案已成功写入文件但两次，有人知道这是为什么吗？除了 main() 之外，如果我在其他任何地方尝试，它只写一次，main 中发生了什么。

Answer 1

查看此 Link .它解释了主要功能的使用。

main is a function that is where every C or C-based program begins. It is a reserved name, which means that you can’t have a function named main. The word int that precedes main is a declaration of the return type of the function.

int main (int argc, const char * argv[])
{
        // memory management
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
        // printing on the log
        NSLog (@"Hello, World!");

       [pool drain];
//The final line tells the main method to return the value 0. Remember that the int the preceded main tells the system that this function will return a value. This value is 0. By convention, a return value of zero indicates that the function was successful.
       return 0;
}

另见 NSAutoreleasePool