在 C++ 中检查 stoi() 函数中的 int 限制
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Checking the int limits in stoi() function in C++
提问by Manmeet Saluja
I have been given a string y in which I'm ensured that it only consists digits. How do I check if it exceeds the bounds of an integer before storing it in an int variable using the stoi function?
我得到了一个字符串 y，其中我确保它只包含数字。在使用 stoi 函数将其存储在 int 变量中之前，如何检查它是否超出了整数的范围？
string y = "2323298347293874928374927392374924"
int x = stoi(y); // The program gets aborted when I execute this as it exceeds the bounds
// of int. How do I check the bounds before I store it?
回答by 4pie0
you can use exception handling mechanism:
您可以使用异常处理机制：
#include <stdexcept>
std::string y = "2323298347293874928374927392374924"
int x;
try {
x = stoi(y);
}
catch(std::invalid_argument& e){
// if no conversion could be performed
}
catch(std::out_of_range& e){
// if the converted value would fall out of the range of the result type
// or if the underlying function (std::strtol or std::strtoull) sets errno
// to ERANGE.
}
catch(...) {
// everything else
}
detailed description of stoi function and how to handle errors
回答by Sani Singh Huttunen
Catch the exception:
捕捉异常：
string y = "2323298347293874928374927392374924"
int x;
try {
x = stoi(y);
}
catch(...) {
// String could not be read properly as an int.
}
回答by Pete Becker
If there is a legitimate possibility that the string represents a value that's too large to store in an int, convert it to something larger and check whether the result fits in an int:
如果字符串表示的值太大而无法存储在 中int，则将其转换为更大的值并检查结果是否适合int：
long long temp = stoll(y);
if (std::numeric_limits<int>::max() < temp
|| temp < std::numeric_limits<int>::min())
throw my_invalid_input_exception();
int i = temp; // "helpful" compilers will warn here; ignore them.
