我已经很难解决这个问题了。我的if / else if语句一直存在问题。在我的程序中，我试图为电话推销员循环列出客户清单，以读取呼叫信息并将其记录到另一个文档中。我只有两个我认为相对较小和较小的问题，但我无法通过Google fu来解决。
这是我的代码：
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
int main()
{
char stat, answ;
float rate;
string fname, lname, phone, address;
ifstream potentials("C:\\Users\\Brandon\\Desktop\\C++Projects\\Lab6\\potentials.txt");
ofstream results("C:\\Users\\Brandon\\Desktop\\C++Projects\\lab6\\results.txt");
if (!potentials) {
cerr << "Unable to open file";
exit(1);
}
while (!potentials.eof())
{
potentials >> stat >> fname >> lname >> phone;
if (stat == 'X')
{
cout << "customer is preferred\n";
rate = .079;
}
if (stat != 'X')
{
cout << "Customer is not preferred\n";
rate = .129;
}
cout << fname << " " << lname << " " << phone << " " << rate << endl;
cout << "Is this customer interested in this card? Y or N" << endl;
cin >> answ;
if (answ == 'Y')
{
cout << "Thank the customer and ask for their current address.\n";
cin >> address;
cout << "Thank the customer for accepting the offer, to expect a card in the mail soon, and happy charging!\n";
results << fname << " " << lname << " " << stat << " " << address << " \r " << endl;
}
if (answ == 'N')
{
if (stat == 'X')
{
cout << "Tempt them with the cash back rewards and to call 18003838383 for a better offer.\n";
results << fname << " " << lname << " " << answ << " " << address << " \r" << endl;
}
else if (stat != 'X');
{
cout << "Tell them thank you anyhow and to have a nice day.\n";
results << fname << " " << lname << " " << answ << " " <<
address << " \r" << endl;
}
}
}
}
问题1：
对于地址部分，如果包含正常的地址（例如123 w main st），则会不断出现错误。那种地址会怪异地完成循环。像[so] [1]。我不知道为什么会这样。如果我只输入一个数字，它将编译并执行得很好。
问题2：
如果客户继续呼叫和拒绝该卡，则将同时执行if语句和else if语句：
customer is preferred
Joe SCholz 437-4798 0.079
Is this customer interested in this card? Y or N
Y
Thank the customer and ask for their current address.
123 W Main St
Thank the customer for accepting the offer, to expect a card in the mail soon, and happy charging!
Customer is not preferredTim Wade 768-7658 0.129
Is this customer interested in this card? Y or N
customer is preferredSara JObs 326-7857 0.079
Is this customer interested in this card? Y or N
Customer is not preferredJaynce Bee 354-8678 0.0129
Is this customer interested in this card? Y or N
我也不理解这部分，因为应该执行if语句。如果客户在文件中的状态上没有X，则应该自动转到else if语句。相反，它同时执行if和else if语句，我似乎无法弄清楚为什么会发生这种情况。
这是让我退缩的仅有的两件事，我都无法弄清。
答案 0 :(得分：0)
if语句后的分号引起了问题。同样，if / else逻辑没有仔细排除并处理所有可能的答案选择。最后，我将std :: getline（）用于std :: cin的读取，当您希望从cin读取的输入有多个单词时，效果更好。
让我知道这是否有帮助。
#include <iostream>
#include <fstream>
#include <cstdlib>
int main()
{
char stat, answ;
float rate;
std::string fname, lname, phone, address, partial_address;
std::ifstream potentials("C:\\Users\\Brandon\\Desktop\\C++Projects\\Lab6\\potentials.txt");
std::ofstream results("C:\\Users\\Brandon\\Desktop\\C++Projects\\lab6\\results.txt");
if (!potentials) {
std::cerr << "Unable to open file ";
return 1;
}
while ( true)
{
// This 'if' statement removes the while(!potentials.eof()) which created an extra read error
// There are other ways to handle this, but this was a quick solution. The read itself will return
// a false value, but as we are trying to read 4 variables, this was one way of doing it.
if(!(potentials >> stat &&
potentials >> fname &&
potentials >> lname &&
potentials >> phone)) {
std::cout << "End of file." << std::endl;
return -1;
}
// if you get into the habit of putting the constant on the left side of an equality,
// you won't accidentally confuse '=' with '=='
if ( 'X' == stat)
{
std::cout << "customer is preferred\n";
rate = .079;
} else if('Y' == stat) { // I usually only check for the value you are looking for, but this is OK, if you create the catch-all else at the end.
std::cout << "Customer is not preferred\n";
rate = .129;
} else {
std::cout << "File corrupted. First word in each line must be 'Y' or 'X'" << std::endl;
return -1; // exit the program as the file is corrupted
}
std::cout << fname << " " << lname << " " << phone << " " << rate << std::endl;
std::cout << "Is this customer interested in this card? Y or N" << std::endl;
std::cin >> answ;
if ('Y' == answ || 'y' == answ) // Just has to check for lower case as well You can chuck that if you like
{
std::cin.ignore(); // cin has a tendency to skip the next input based on a prior "return" or "enter". Gobble the new line
std::cout << "Thank the customer and ask for their current address.\n";
std::getline(std::cin, address);
std::cout << "Thank the customer for accepting the offer, to expect a card in the mail soon, and happy charging!\n";
results << fname << " " << lname << " " << stat << " " << address << " \r " << std::endl;
} else if('N' == answ || 'n' == answ) {
// AT this point, we already know that stat is either 'Y' or 'N', so we don't check explicitly on the else
if ('X' == stat)
{
std::cout << "Tempt them with the cash back rewards and to call 18003838383 for a better offer.\n";
results << fname << " " << lname << " " << answ << " " << address << " \r" << std::endl;
} else {
std::cout << "Tell them thank you anyhow and to have a nice day.\n";
results << fname << " " << lname << " " << answ << " " <<
address << " \r" << std::endl;
}
} else { // catch all else. Not my preferred way to do this, but follows your design.
std::cout << "Invalid response. Response must be 'Y' or 'X'" << std::endl;
return -1; // exit the program as the response was not corrupted
}
}
}