2021-09-07

1.main主函数的形参

int main()
{
}

int main(int argc, char* argv[])
{
}

argc：将应用程序作为字符串

*argv[]：数组，存放地址；在主函数中开辟空间

int main(int argc, char* argv[], char* engv[])
{
}

argc：将应用程序作为字符串

*argv[]：数组，存放地址；在主函数中开辟空间

*engv[]：当前系统环境变量

int main(int argc,char *argv[])
{
	printf("%d \n", argc);
	for (int i = 0; i < argc; ++i)
	{
		printf("%s \n", argv[i]);
	}
	return 0;
}

2.main主函数形参与文件

int main(int argc, char* argv[]) 
{
	char ch;
	if (argc < 3) return 1;

	FILE* fpr = nullptr, * fpw = nullptr;
	errno_t tag = fopen_s(&fpr, argv[1], "rb");
	if (nullptr == fpr)
	{
		printf("src file error %d \n", tag);
		return 1;
	}
	tag = fopen_s(&fpw, argv[2], "wb");
	if (nullptr == fpw)
	{
		printf("dest file error %d \n", tag);
		return 1;
	}
	fseek(fpr, 0, SEEK_END);
	int len = ftell(fpr);
	rewind(fpr);
	char* str = (char*)malloc(sizeof(char) * len);
	fread(str, sizeof(char), len, fpr);

	fwrite(str, sizeof(char), len, fpw);

	fclose(fpr);
	fclose(fpw);
	fpr = fpw = nullptr;
	return 0;
}