技術標籤：C++c++

1.輸入錯誤

If the user has entered invalid input, ask the user to enter the input again.

#include <iostream>
#include <limits>
#include <string>
 
int main()
{
    std::string hello{ "Hello, world!" };
    int index;
 
    do
    {
        std::cout << "Enter an index: "
 
;
        std::cin >> index;
 
        //handle case where user entered a non-integer
        if (std::cin.fail())
        {
            std::cin.clear(); // reset any error flags
            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); 
            // ignore any characters in the input buffer
 

            index = -1;
             // ensure index has an invalid value so the loop doesn't terminate
            continue; // this continue may seem extraneous,
            // but it explicitly signals an intent to terminate this loop iteration...
        }
 
        // ...just in case we added more stuff here later
 

 
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); 
        // ignore any remaining characters in the input buffer
 
    } while (index < 0 || index >= static_cast<int>(hello.size())); 
    // handle case where user entered an out of range integer
 
    std::cout << "Letter #" << index << " is " << hello[index] << '\n';
 
    return 0;
}

2.輸出流為NULL

Quietly skip the code that depends on the assumption being valid:

void printString(const char *cstring)
{
    // Only print if cstring is non-null
    if (cstring)
        std::cout << cstring;
}

3.錯誤的返回值

return an error code back to the caller and let the caller deal with the problem

#include <array>
 
// assume the array only holds positive values
int getArrayValue(const std::array<int, 10> &array, int index)
{
    // use if statement to detect violated assumption
    if (index < 0 || index >= static_cast<int>(array.size()))
       return -1; // return error code to caller
 
    return array[index];
}