9/1/2023 0 Comments Cpp string to int![]() If idx is not a null pointer, the function also sets the value of idx to the position of the first character in str after the number. Different methods to convert the string data into integers in the C++ programming language. If you're writing C++, you should do that anyway, but it kind of forces the issue. Convert string to unsigned integer Parses str interpreting its content as an integral number of the specified base, which is returned as an unsigned long value. This function accepts a number (which can be any data type) and returns the number as the desired string. The biggest expense is that it can throw exceptions, so to use it your code has to be exception-safe. The tostring () function can be used to convert an integer, floating point values, or any number to a string. This is almost as simple to use as atoi, but also provides (roughly) the same level of detail in reporting errors as strtol. Since you're using C++, you could also consider using boost::lexical_cast. As an aside, you really dont want to use strlen(s) inside the stopping condition for your for-loop. When you do math on it, itll normally be converted to int automatically, so you dont even need your cast. Note that strtol does give slightly more detailed results though - in particular, if you got an argument like 123abc, the sscanf call would simply say it had converted a number (123), whereas strtol would not only tel you it had converted the number, but also a pointer to the a (i.e., the beginning of the part it could not convert to a number). Yes - in C and C++, char is just a small integer type (typically with a range from -128 to +127). Another possibility would be to use sscanf, something like: if (1=sscanf(argv, "%d", &temp)) sscanf (hexString, 'x', &hexNumber) This works just perfectly fine (provided you use appropriate data types per your need). ![]() He also recommended strtol, which is perfectly fine, if a little bit clumsy. const char hexString '7FFEA5' //Just to show the conversion of a bigger hex number unsigned long hexNumber //In case your hex number is going to be sufficiently big. The first is clearly meaningful, but the second is a clear error. The best you can do is convert n s value to int and store the result in a new int variable. For example, you cannot change n s type to int. Its incorrect to believe staticcast can be used to change the type of a variable. atoi has no way to indicate an error, so you get the same return from atoi("0") as you do from atoi("abc"). To directly answer the titles question, the usage of staticcast you are looking for is int i staticcast (n).All except atoi reject trailing whitespace.Īs WhirlWind has pointed out, the recommendations to use atoi aren't really very good. ![]() We create a variable of output string stream class and create a variable str. ![]() All accept leading whitespace check isspace(argv) if you don't want that. It is used to hold the number entered by the user. The C way simplest, but will treat any invalid number as 0: #include Since this answer was somehow accepted and thus will appear at the top, although it's not the best, I've improved it based on the other answers and the comments. ![]()
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