我之所以重新发布，是因为我的上一则帖子由于格式不正确而被关闭；希望这是固定的。
当我给它正确的输入，即一个带有8、16、24或32子掩码的IPv4时，它什么也不做，当我按Enter键时仍然接受输入，而它显然应该返回广播IP的输出。在以下代码中出现此错误，我在做什么错？我已经尝试过调试器，但是到目前为止，它们都没有帮助我解决问题。这是用于分配的，并且不允许使用数组。
#include <stdio.h>
int IPAndSubnetMaskInput(int IPAndSubnetMaskFirstOctate, int IPAndSubnetMaskSecondOctate, int IPAndSubnetMaskThirdOctate, int IPAndSubnetMaskFourthOctate, int IPAndSubnetMaskSubnetInput) {
printf("Please input an IPv4 address followed by the subnetmask (must either be 8, 16, 24, or 32) in the following format: 192 168 1 1 32: \n"); //Statement to ask for IP and submask input and puts the inputs into a variable to calculate Broadcast IP
int IPv4AndSubmask = scanf("%d %d %d %d %d", &IPAndSubnetMaskFirstOctate, &IPAndSubnetMaskSecondOctate, &IPAndSubnetMaskThirdOctate, &IPAndSubnetMaskFourthOctate, &IPAndSubnetMaskSubnetInput); //Input function
while (!(IPAndSubnetMaskSubnetInput == 8 || IPAndSubnetMaskSubnetInput == 16 || IPAndSubnetMaskSubnetInput == 24 || IPAndSubnetMaskSubnetInput == 32)) { //Initializing loop to evaluate whether subnet is correct or not
printf("Your submask is wrong. Please enter a value that's either 8, 16, 24, or 32: \n");
IPAndSubnetMaskSubnetInput = scanf("%d", &IPAndSubnetMaskSubnetInput);
if (IPAndSubnetMaskSubnetInput == 8 || IPAndSubnetMaskSubnetInput == 16 || IPAndSubnetMaskSubnetInput == 24 || IPAndSubnetMaskSubnetInput == 32)
{
break;
}
}
return IPv4AndSubmask;//function returns the value of IP octates and the subnet mask for the program to calculate
}
int broadcastCalculator(int broadcastFirstOctate, int broadcastSecondOctate, int broadcastThirdOctate, int broadcastFourthOctate, int broadcastSubnetInput) { //Declaration of first function for first Assignment point
IPAndSubnetMaskInput(broadcastFirstOctate, broadcastSecondOctate, broadcastThirdOctate, broadcastFourthOctate, broadcastSubnetInput);
while (0 == 0) {
if (broadcastSubnetInput == 8) { //Conditional statement for submask of 8
printf("The broadcast IP is:\t%hhu\t%hhu\t%hhu\t255\t\n", broadcastFirstOctate, broadcastSecondOctate, broadcastThirdOctate);//Program will print the Broadcast IP of firstOctate secondOctate thirdOctate 255
break;
}
else if (broadcastSubnetInput == 16) {//Conditional statement for submask of 16
printf("The broadcast IP is:\t%hhu\t%hhu\t255\t255\t\n", broadcastFirstOctate, broadcastSecondOctate);//Program will print the Broadcast IP of firstOctate secondOctate 255 255
break;
}
else if (broadcastSubnetInput == 24) {//Conditional statement for submask of 24
printf("The broadcast IP is:\t%hhu\t255\t255\t255\t\n", broadcastFirstOctate);//Program will print the Broadcast IP of firstOctate 255 255 255
break;
}
else if (broadcastSubnetInput == 32) {//Conditional statement for submask of 32
printf("The broadcast IP is:\t255\t255\t255\t255");//Program will print the Broadcast IP of 255 255 255 255
break;
}
}
return 0;
}
int main()
{
int FARfirstOctate = 0; int FARsecondOctate = 0; int FARthirdOctate = 0; int FARfourthOctate = 0; int FARsubnetInput = 0;
broadcastCalculator(FARfirstOctate, FARsecondOctate, FARthirdOctate, FARfourthOctate, FARsubnetInput);
return 0;
}
最佳答案
您的代码中有几个问题！第一个（也是最严重的）错误是您正在按值传递值-这意味着函数将接收数据的“副本”，并且无法更改调用代码中的值。要解决此问题，您需要将参数声明为指针，并传递变量的地址以进行更改。
您（在少数地方）遇到的另一个问题是，您正在为变量分配scanf函数的返回值：这是错误的，因为这将是scanf读取（成功）了多少个值的计数。
这是代码的“固定”版本，在我进行了更改的地方加上了三斜杠注释（///），并加上了注释：
#include <stdio.h>
/// Declare the arguments as POINTERS - so we can change the values in the calling code ...
int IPAndSubnetMaskInput(int* IPAndSubnetMaskFirstOctate,
int* IPAndSubnetMaskSecondOctate,
int* IPAndSubnetMaskThirdOctate,
int* IPAndSubnetMaskFourthOctate,
int* IPAndSubnetMaskSubnetInput)
{
printf("Please input an IPv4 address followed by the subnetmask (must either be 8, 16, 24, or 32) in the following format: 192 168 1 1 32: \n"); //Statement to ask for IP and submask input and puts the inputs into a variable to calculate Broadcast IP
/// This line WAS WRONG - the return value from scanf is the COUNT of values read!
int IPv4AndSubmask = 0; /// We need to do something here to get a meaningful return value
scanf("%d %d %d %d %d", /// As they are ALREADY pointers now, we don't need the addresses ...
IPAndSubnetMaskFirstOctate,
IPAndSubnetMaskSecondOctate,
IPAndSubnetMaskThirdOctate,
IPAndSubnetMaskFourthOctate,
IPAndSubnetMaskSubnetInput); //Input function
while (!(*IPAndSubnetMaskSubnetInput == 8 || /// As they're now all POINTERS, we need to dereference them...
*IPAndSubnetMaskSubnetInput == 16 ||
*IPAndSubnetMaskSubnetInput == 24 ||
*IPAndSubnetMaskSubnetInput == 32))
{ //Initializing loop to evaluate whether subnet is correct or not
printf("Your submask is wrong. Please enter a value that's either 8, 16, 24, or 32: \n");
/// This line is WRONG - the return value from scanff is the COUNT of values read!
// IPAndSubnetMaskSubnetInput = scanf("%d", IPAndSubnetMaskSubnetInput);
scanf("%d", IPAndSubnetMaskSubnetInput); /// Already a pointer!
/// We don't need this check - the loop will exit when the condition is matched!
// if (*IPAndSubnetMaskSubnetInput == 8 || /// As they're now all POINTERS, we need to dereference them...
// *IPAndSubnetMaskSubnetInput == 16 ||
// *IPAndSubnetMaskSubnetInput == 24 ||
// *IPAndSubnetMaskSubnetInput == 32)
// {
// break;
// }
}
return IPv4AndSubmask;//function returns the value of IP octates and the subnet mask for the program to calculate
}
/// Declare theargumetns as POINTERS - so we can change the values in the calling code ...
int broadcastCalculator(int* broadcastFirstOctate,
int* broadcastSecondOctate,
int* broadcastThirdOctate,
int* broadcastFourthOctate,
int* broadcastSubnetInput)
{ //Declaration of first function for first Assignment point
IPAndSubnetMaskInput(broadcastFirstOctate,
broadcastSecondOctate,
broadcastThirdOctate,
broadcastFourthOctate,
broadcastSubnetInput);
while (0 == 0) {
/// As before, we now need to DEREFENCE the pointers...
if (*broadcastSubnetInput == 8) { //Conditional statement for submask of 8
printf("The broadcast IP is:\t%hhu\t%hhu\t%hhu\t255\t\n",
*broadcastFirstOctate,
*broadcastSecondOctate,
*broadcastThirdOctate);
//Program will print the Broadcast IP of firstOctate secondOctate thirdOctate 255
break;
}
else if (*broadcastSubnetInput == 16) {//Conditional statement for submask of 16
printf("The broadcast IP is:\t%hhu\t%hhu\t255\t255\t\n",
*broadcastFirstOctate,
*broadcastSecondOctate);
//Program will print the Broadcast IP of firstOctate secondOctate 255 255
break;
}
else if (*broadcastSubnetInput == 24) {//Conditional statement for submask of 24
printf("The broadcast IP is:\t%hhu\t255\t255\t255\t\n",
*broadcastFirstOctate);
//Program will print the Broadcast IP of firstOctate 255 255 255
break;
}
else if (*broadcastSubnetInput == 32) {//Conditional statement for submask of 32
printf("The broadcast IP is:\t255\t255\t255\t255");
//Program will print the Broadcast IP of 255 255 255 255
break;
}
}
return 0;
}
int main()
{
int FARfirstOctate = 0; int FARsecondOctate = 0; int FARthirdOctate = 0; int FARfourthOctate = 0; int FARsubnetInput = 0;
broadcastCalculator(&FARfirstOctate, &FARsecondOctate, &FARthirdOctate, &FARfourthOctate, &FARsubnetInput);
return 0;
}
随时要求进一步的澄清和/或解释。
关于c - C程序没有从“正确的”输入中给出所需的输出，而是在给出，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/59111022/