从char*到int的转换无效。C++错误；
我在这里感到困惑。为什么我会犯这个错误从char*到int的转换无效。C++错误；,c++,do-while,C++,Do While,我在这里感到困惑。为什么我会犯这个错误 Running /home/ubuntu/workspace/main.cpp /home/ubuntu/workspace/main.cpp: In function ‘int main()’: /home/ubuntu/workspace/main.cpp:22:19: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive] case "-"
Running /home/ubuntu/workspace/main.cpp
/home/ubuntu/workspace/main.cpp: In function ‘int main()’:
/home/ubuntu/workspace/main.cpp:22:19: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive]
case "-" :
^
/home/ubuntu/workspace/main.cpp:22:19: error: ‘(int)((long int)"-")’ is not a constant expression
/home/ubuntu/workspace/main.cpp:31:19: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive]
case "*" :
^
/home/ubuntu/workspace/main.cpp:31:19: error: ‘(int)((long int)"*")’ is not a constant expression
/home/ubuntu/workspace/main.cpp:40:19: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive]
case "/" :
^
/home/ubuntu/workspace/main.cpp:40:19: error: ‘(int)((long int)"/")’ is not a constant expression
/home/ubuntu/workspace/main.cpp:50:14: error: no match for ‘operator>>’ (operand types are ‘std::ostream {aka std::basic_ostream<char>}’ and ‘const char [41]’)
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
/home/ubuntu/workspace/main.cpp:50:14: note: candidates are:
In file included from /usr/include/c++/4.8/string:53:0,
from /usr/include/c++/4.8/bits/locale_classes.h:40,
from /usr/include/c++/4.8/bits/ios_base.h:41,
from /usr/include/c++/4.8/ios:42,
from /usr/include/c++/4.8/ostream:38,
from /usr/include/c++/4.8/iostream:39,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/bits/basic_string.tcc:996:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::basic_string<_CharT, _Traits, _Alloc>&)
operator>>(basic_istream<_CharT, _Traits>& __in,
^
/usr/include/c++/4.8/bits/basic_string.tcc:996:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<_CharT, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/istream:882:0,
from /usr/include/c++/4.8/iostream:40,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/bits/istream.tcc:955:5: note: template<class _CharT2, class _Traits2> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT2*)
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
^
/usr/include/c++/4.8/bits/istream.tcc:955:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<_CharT, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/istream:882:0,
from /usr/include/c++/4.8/iostream:40,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/bits/istream.tcc:923:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&)
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
^
/usr/include/c++/4.8/bits/istream.tcc:923:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<_CharT, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/iostream:40:0,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/istream:727:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char&)
operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
^
/usr/include/c++/4.8/istream:727:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<char, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/iostream:40:0,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/istream:732:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char&)
operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
^
/usr/include/c++/4.8/istream:732:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<char, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/iostream:40:0,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/istream:774:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*)
operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
^
/usr/include/c++/4.8/istream:774:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<char, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/iostream:40:0,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/istream:779:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*)
operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
^
/usr/include/c++/4.8/istream:779:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<char, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
In file included from /usr/include/c++/4.8/iostream:40:0,
from /home/ubuntu/workspace/main.cpp:1:
/usr/include/c++/4.8/istream:872:5: note: template<class _CharT, class _Traits, class _Tp> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&&, _Tp&)
operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
^
/usr/include/c++/4.8/istream:872:5: note: template argument deduction/substitution failed:
/home/ubuntu/workspace/main.cpp:50:17: note: ‘std::ostream {aka std::basic_ostream<char>}’ is not derived from ‘std::basic_istream<_CharT, _Traits>’
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
^
#include <iostream>
using namespace std;
int main(){
char option,continueCheck;
int a,b,res;
cout << "********** Welcome to the operation game ********* " <<endl;
do{
cout << "Please type (+,-,/,*) to add your numbers " <<endl;
cin >> option;
switch(option){
case '+' :
cout << "Please type in the first number" <<endl;
cin >> a;
cout << "Please type in the second number" <<endl;
cin >> b;
res = a+b;
printf("%d + %d = %d \n" , a,b,res);
break;
case "-" :
cout << "Please type in the first number" <<endl;
cin >> a;
cout << "Please type in the second number" <<endl;
cin >> b;
res = a-b;
printf("%d + %d = %d \n" , a,b,res);
break;
case "*" :
cout << "Please type in the first number" <<endl;
cin >> a;
cout << "Please type in the second number" <<endl;
cin >> b;
res = a*b;
printf("%d + %d = %d \n" , a,b,res);
break;
case "/" :
cout << "Please type in the first number" <<endl;
cin >> a;
cout << "Please type in the second number" <<endl;
cin >> b;
res = a/b;
printf("%d + %d = %d \n" , a,b,res);
break;
}
cout >> "Want to continue? Enter Y or y OR N or n" << endl;
cin >> continueCheck;
}while(continueCheck = 'y');
}
我的意思是我显然没有把字符转换成int。我甚至都没学会怎么做。好像我在这里很困惑。它认为“+”是一个int还是什么？在您的例子中，您使用的是双引号，对应于const char*。您希望使用单引号，即字符 它抱怨从const char*转换为int的原因是char被提升为int类型 不过，您的程序还有许多其他问题 您所有的printf都打印相同的内容，但75%的时间不正确 您需要使用双等于来检查while中的相等性
您在std:：cout的末尾使用了一个extraction操作符>>，在您的例子中，应该是，您使用的是双引号，它对应于const char*。您希望使用单引号，即字符 它抱怨从const char*转换为int的原因是char被提升为int类型 不过，您的程序还有许多其他问题 您所有的printf都打印相同的内容，但75%的时间不正确 您需要使用双等于来检查while中的相等性 您在std:：cout的末尾使用了提取运算符>>，应该可能是键入错误！？ 第22行：编译器在这个位置需要一个整数，但这是一个字符串，一个指针。 第13行：按如下方式键入：“-”可能是键入错误！？ 第22行：编译器在这个位置需要一个整数，但这是一个字符串，一个指针。
第13行：按如下方式键入：“-”在“-”和-”之间存在子空间差异： 前者是char类型的单个整数，值为45 ASCII值- 后者是一个字符串。字符串的内容是一个2元素数组{45,0}，其中45是-的ASCII码，0表示字符串的结尾。字符串的值作为一个整体是指向存储它的内存的指针。 实际上，代码试图做的是将option的值与指向内存的指针进行比较。解决方法是更改引号 代码中还有其他错误，最突出的是
while(continueCheck = 'y')
它将值“y”指定给continueCheck，如果指定的值为非零（始终为真），则继续循环。您很可能希望将continueCheck与y进行比较，y是通过运算符==，而不是=。在“-”和-”之间存在子空间差异： 前者是char类型的单个整数，值为45 ASCII值- 后者是一个字符串。字符串的内容是一个2元素数组{45,0}，其中45是-的ASCII码，0表示字符串的结尾。字符串的值作为一个整体是指向存储它的内存的指针。 实际上，代码试图做的是将option的值与指向内存的指针进行比较。解决方法是更改引号 代码中还有其他错误，最突出的是
while(continueCheck = 'y')
它将值“y”指定给continueCheck，如果指定的值为非零（始终为真），则继续循环。您很可能希望将continueCheck与y进行比较，y是通过运算符==，而不是=。case-→ 案例“-”等。非常感谢@Biffen！案例-→ 案例“-”等。非常感谢@Biffen！whilecontinueCheck='y'；这也是错误的。由于OP写了“+”但是-等等，我认为OP只需要更加关注他/她的代码。我的意思是，我显然没有在任何地方将char转换为int。是的，OP试图，但没有意识到。因为这正是凯斯所期望的。@LightnessRacesinOrbit刚刚发布了一个仓促的回答。我们将列举程序中的其他问题，但这是最紧迫的问题不是批评，只是聊天。虽然FGITW=不好，但现在您提到了：P@LightnessRacesinOrbit为了完整起见，我添加了我能找到的所有逻辑问题。没有提到风格或最佳实践：whilecontinueCheck='y'；这也是错误的。由于OP写了“+”但是-等等，我认为OP只需要更加关注他/她的代码。我的意思是，我显然没有在任何地方将char转换为int。是的，OP试图，但没有意识到。因为这正是凯斯所期望的。@LightnessRacesinOrbit刚刚发布了一个仓促的回答。我们将列举程序中的其他问题，但这是最紧迫的问题不是批评，只是聊天。虽然FGITW=不好，但现在您提到了：P@LightnessRacesinOrbit为了完整起见，我添加了我能找到的所有逻辑问题。没有提到风格或最佳实践：这应该是一个评论。问题是：我为什么会犯这个错误？答案应该是肯定的，而不是可能的。这应该是一个评论。问题是：我为什么会犯这个错误？答案应该是肯定的，而不是可能的。