C++11 has the std::stoi
, std::stol
, and std::stoll
functions, which throw an exception if the string cannot be converted.
Is a given string convertable to an integer [duplicate]
Question
Is there an effective way in C to check if a given string is convertable to an integer?
An output error should indicate if the string is convertable or not.
For example, "aa" is not convertable, "123" is convertable.
Solution
OTHER TIPS
With C, use the strtol(3) function with an end pointer:
char* end=NULL;
long l = strtol(cstr, &end, 0);
if (end >= cstr && *end)
badnumber = true;
else
badnumber = false;
With C++11, use the std::strtol function (it raises an exception on failure).
You could also loop through the string and appply isdigit
function to each character
bool is_convertible_to_int(const std::string &s) {
try {
int t = std::stoi(s);
return std::to_string(t).length() == s.length();
}
catch (std::invalid_argument) {
return false;
}
}
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