如何从用户而不是示例中获取输入字符串，然后计算空格，标点符号，数字和字母。 C ++

Question

This is my code. User will give an input(any string) instead of the "This is a test. 1 2 3 4 5".

Then it will show number of spaces, punctuation, digits, and letters as output string.

#include <iostream>
#include <cctype>

using namespace std;

int main() {

const char *str = "This is a test. 1 2 3 4 5";
int letters = 0, spaces = 0, punct = 0, digits = 0;

cout << str << endl;
while(*str) {
if(isalpha(*str)) 
   ++letters;
else if(isspace(*str)) 
   ++spaces;
else if(ispunct(*str)) 
   ++punct;
else if(isdigit(*str)) 
   ++digits;
++str;
}
cout << "Letters: " << letters << endl;
cout << "Digits: " << digits << endl;
cout << "Spaces: " << spaces << endl;
cout << "Punctuation: " << punct << endl;

return 0;
}

Answer 1

You want to use std::getline in conjunction with std::cin which reads from the standard C input stream stdin

• std::getline reads characters from an input stream and places them into a string
• std::cin is the input stream associated with stdin

Typically you want to output a prompt to the user:

std::cout << "Please enter your test input:\n";

Then you want to create a std::string , and use std::getline with std::cin to store the user's input into that string:

std::string input;
std::getline(std::cin, input);

At this point your program will block until the user types in their input, and presses enter.

Once the user presses enter, std::getline will return, and you can do whatever you want with the contents of the string

Example:

#include <iostream>
#include <cctype>

using namespace std;

int main()
{
    std::cout << "Enter the test input:\n";
    std::string input;
    std::getline(std::cin, input);

    const char *str = input.c_str();
    int letters = 0, spaces = 0, punct = 0, digits = 0;

    cout << str << endl;
    while(*str) {
        if(isalpha(*str))
            ++letters;
        else if(isspace(*str))
            ++spaces;
        else if(ispunct(*str))
            ++punct;
        else if(isdigit(*str))
            ++digits;
        ++str;
    }
    cout << "Letters: " << letters << endl;
    cout << "Digits: " << digits << endl;
    cout << "Spaces: " << spaces << endl;
    cout << "Punctuation: " << punct << endl;

    return 0;
}

Output:

$ ./a.out 
Enter the test input:
This is a test 1 2 3 4
This is a test 1 2 3 4
Letters: 11
Digits: 4
Spaces: 7
Punctuation: 0