在C++上指數的LLDB錯誤

Question

我更新了我的計算器代碼，並添加了指數函數。然而，當我嘗試獲得方程的答案時，我得到這個錯誤： （lldb） 任何幫助將不勝感激，因爲這是我第一天用C++！是的，就是這樣！ 這是我的代碼！

#include <math.h> 
#include <iostream> 
int int1, int2, answer; 
bool bValue(true); 
std::string oper; 
std::string cont; 
using namespace std; 
std::string typeOfMath; 
int a; 
int b; 
int answerExponent; 


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

// Taking user input, the first number of the calculator, the operator, and second number. Addition, Substraction, Multiplication, Division 
    cout<<"______________________________________________\n"; 
    cout<<"|Welcome to The ExpCalc! Do you want to do |\n"; 
    cout<<"|Exponent Math, or Basic Math(+, -, X, %) |\n"; 
    cout<<"|Type in 'B' for basic Math, and'E' for  |\n"; 
    cout<<"|Exponential Math! Enjoy! (C) John L. Carveth|\n"; 
    cout<<"|____________________________________________|\n"; 
    cin>> typeOfMath; 
    if(typeOfMath == "Basic" || 
     typeOfMath == "basic" || 
     typeOfMath == "b" || 
     typeOfMath =="B") 
    { 
     cout << "Hello! Please Type in your first integer!\n"; 
     cin>> int1; 
     cout<<"Great! Now Enter your Operation: ex. *, /, +, -...\n"; 
     cin>> oper; 
     cout<<"Now all we need is the last int!\n"; 
     cin>> int2; 

     if (oper == "+") { 
      answer = int1 + int2; 
     } 
     if (oper == "-") { 
      answer = int1 - int2; 

     }if (oper == "*") { 
      answer = int1 * int2; 
     }if (oper == "/") { 
      answer = int1/int2; 
     } 
     cout<<answer << "\n"; 
     cout<<"Thanks for Using The ExpCalc!\n"; 

    }else if(typeOfMath == "Exp" ||typeOfMath == "E" ||typeOfMath == "e" ||typeOfMath == "Exponent"){ 
     cout<<"Enter the desired Base. Example: 2^3, where 2 is the base.\n"; 
     cin>> a; 
     cout<<"Now what is the desired exponent/power of the base? Ex. 2^3 where 3 is the exponent!\n"; 
     cin>>b; 
     answerExponent = (pow(a,b)); 
     cout<< answerExponent; 
    } else(cout<<"Wrong String!"); 
} 

請幫忙！我可能會問很多問題，所以請不要生氣！我也在Mac上使用Xcode 4！

Answer 1

添加此行到您的包括：

#include <string>

做完這些後，我能得到的代碼編譯並使用正確的輸出2^3上運行，在這兩個Visual Studio中，並在GCC 4.7.2中使用ideone.com（click here查看輸出）。但是，由於從double到int的轉換，我們的編譯器仍然會發出警告，您應該通過轉換來處理。更改此：

answerExponent = (pow(a,b));

要這樣：

answerExponent = static_cast<int>(pow(a,b));

雖這麼說，編譯器發出的警告是有原因的，並通過鑄造你基本上只是告訴編譯器「無論如何閉嘴，並做它「。更好的方法是避免需要演員。而不是做上述變化，改變這一行：

int answerExponent;

要這樣：

double answerExponent;

這更有意義，因爲很少有一點呼籲pow與double S作爲參數如果你打算扔掉數字的小數部分。