所以我的编程技巧有点生疏，除了我过去的大学课程之外，没有任何现实世界的经验。我正在研究一个类的程序，但遇到了障碍;我无法弄清楚如何在循环外的For循环内使用变量的值。这是我引用的代码：
#include "iostream"
using namespace std;
int want, have, need;
int counter = 0;
char response, cont;
int diff(int want, int have);
int main(){
cout << "Welcome!\n";
cout << "This program will help you reach your money saving goals!\n";
cout << "Would you like to use this program? (y/n)\n";
cin >> response;
while (response == 'y'){
cout << "Please enter all amounts in whole dollars only!\n";
cout << "Please enter the amount of money you would like to have saved: $";
cin >> want;
cout << "\nPlease enter the amount of money you currently have saved: $";
cin >> have;
if (have >= want){
cout << "You have already reached or exceeded your goal, this program will not be able to help you!\n";
system("Pause");
return 0;
}
cout << "\nYou need to save $" << diff(want, have) << " more money to reach your goal!\n";
cout << "Would you like me to help you with a savings plan?";
cin >> cont;
while (cont == 'y'){
int menu;
cout << "Please select from the following options: \n";
cout << "1 - Daily Saving Plan\n";
cout << "2 - Weekly Saving Plan\n";
cout << "3 - Monthly Saving Plan\n";
cout << "Enter the number associated with your choice: \n";
cin >> menu;
switch (menu){
case 1: {
int daily;
cout << "You have chosen the Daily Savings Plan\n";
cout << "How much money can you save every day? $";
cin >> daily;
for (int x = daily; x < need; x++){
daily = daily + daily;
counter++;
}
cout << "\nIt will take you " << counter << " days to reach your goal!\n";
break;
}
case 2: {
int weekly;
cout << "You have chosen the Weekly Savings Plan\n";
cout << "How much money can you save every week? $";
cin >> weekly;
for (int x = weekly; x < need; x++){
counter++;
}
cout << "\nIt will take you " << counter << " weeks to meet your goal!\n";
break;
}
case 3: {
int monthly;
cout << "You have chosen the Monthly Savings Plan\n";
cout << "How much money can you save every month? $";
cin >> monthly;
for (int x = monthly; x < need; x++){
monthly = monthly + monthly;
counter++;
}
cout << "\nIt will take you " << counter << " months to reach your goal!\n";
break;
}
default: cout << "You made an invalid selection";
cout << "Would you like to look at a different saving plan? (y/n)\n";
cin >> cont;
}
}
}
}
int diff(int want, int have){
return want - have;
}
因此，当我运行程序时，一切运行正常，但计数器的值在最终cout语句中始终显示为“0”。
我理解为什么它会这样做，我认为..这是因为循环外的“int counter = 0”声明，所以我假设它在循环退出后返回到该值。
如果我没有启动计数器变量，我会收到一个错误，如果我在循环中声明了这个值，我会在cout语句中尝试使用它，如上所述。
我甚至不确定我的for循环是否正确构造...基本上我希望它将每周变量添加到自身，直到x = need的总和。我还想捕获它需要多少次迭代，然后将其输出为周数。希望一切都有意义;任何和所有的帮助表示赞赏。
答案 0 :(得分：0)
看起来您想要做的事情可以通过ceil(double(need/weekly))完成，并且需要按周计算。
在完成cout循环后，您在循环外的声明不会影响for的值。
至于你的问题，看起来你从未初始化need所以你的for循环从未进行迭代，因为undefined不小于或等于0。
答案 1 :(得分：0)
程序的C ++ 11中的草图。
char prompt( std::initializer_list<const char*> message, std::initializer_list<const char*> question, std::initializer_list<char> options ) {
for( auto msg:message )
std::cout << msg;
while(true) {
char response;
for( auto q:question)
std::cout << q;
std::cin >> response;
for (char option:options) {
if (response == option)
return response;
}
}
}
int prompt( std::initializer_list<const char*> message, std::initializer_list<const char*> question, int min = 0, int max = std::numeric_limits<int>::max() ) {
for( auto msg:message )
std::cout << msg;
while(true) {
int response;
for( auto q:question)
std::cout << q;
std::cin >> response;
if (response >= min && response <= max)
return response;
}
}
}
void saving( const char* plan, const char* unit, const char* units, int target ) {
int daily = prompt(
{"You have chosen the ", plan, "\n"},
{"How much money can you save every ", unit, "? $"},
1 // min saving of 1$ per unit time to prevent infinite loops
);
std::cout << "\n";
int counter = 0;
int amount_saved = 0;
while (amount_saved < target) {
++counter;
amount_saved += daily;
}
if (counter != 1)
std::cout << "It will take you " << counter << " " << units << " to reach your goal\n";
else
std::cout << "It will take you " << counter << " " << unit << " to reach your goal\n";
}
int main() {
while(
prompt(
{"Welcome!\nThis program will help you reach your money saving goals!\n"},
{"Would you like to use this program? (y/n)\n"},
{'y', 'n'}
) == 'y'
)
{
int want = prompt( {"Please enter all amounts in whole dollars only!\n"},
{"Please enter the amount of money you would like to have saved?"} );
int have = prompt( {"\n"}, {"Please enter the amount of money you currently have saved?\n"} );
std::cout << "\n";
if (have >= want) {
std::cout << "You win!\n";
system("Pause"); // ick
return 0;
}
std::cout << "You need to save $" << (have-want) << " more money to reach your goal!\n";
while( 'y' == prompt(
{},
{"Would you like me to help you with a savings plan? (y/n)"},
{ 'y', 'n' }
)) {
char menu = prompt(
{
"Please select from the following options: \n",
"1 - Daily Saving Plan\n",
"2 - Weekly Saving Plan\n",
"3 - Monthly Saving Plan\n"
},
{"Enter the number associated with your choice: \n"},
{ '1', '2', '3' }
);
switch (menu) {
case '1': {
saving( "Daily Saving Plan", "day", "days", have-want);
} break;
case '2: {
saving( "Weekly Saving Plan", "week", "weeks", have-want);
} break;
case '3': {
saving( "Monthly Saving Plan", "month", "months", have-want);
} break;
}
}
}
}