将数字字符串中的数字转换为整数，然后转换为数组

Question

我有一个 1000 位的数字，我将其存储为一个字符串。我想将该数字中的每个数字作为向量中它自己的元素结束。所以“12345”将是 {1,2,3,4,5}。这是我到目前为止的代码，但它不起作用。错误来自将字符串字母与数字进行比较。任何帮助，将不胜感激。我看到另一个类似的问题，但是字符串包含数字之间的空格，这个没有。

#include "stdafx.h"
#include <iostream>
#include <vector>
#include <sstream>
#include <string>

int main()
{


std::string input_string = "73167176531330624919225119674426574742355349194934"
"96983520312774506326239578318016984801869478851843"
"85861560789112949495459501737958331952853208805511"
"12540698747158523863050715693290963295227443043557"
"66896648950445244523161731856403098711121722383113"
"62229893423380308135336276614282806444486645238749"
"30358907296290491560440772390713810515859307960866"
"70172427121883998797908792274921901699720888093776"
"65727333001053367881220235421809751254540594752243"
"52584907711670556013604839586446706324415722155397"
"53697817977846174064955149290862569321978468622482"
"83972241375657056057490261407972968652414535100474"
"82166370484403199890008895243450658541227588666881"
"216427171479924442928230863465674813919123162824586"
"17866458359124566529476545682848912883142607690042"
"24219022671055626321111109370544217506941658960408"
"07198403850962455444362981230987879927244284909188"
"84580156166097919133875499200524063689912560717606"
"05886116467109405077541002256983155200055935729725"
"71636269561882670428252483600823257530420752963450";

std::cout << "storing string" << std::endl;

std::vector<int> return_vector;

for (int i = 0; i<1000; i++)
{
    if (&input_string[i] == "0")
    {
        std::cout << 0 << std::endl;
        return_vector.push_back(0);
    }

    if (&input_string[i] == "1")
    {
        return_vector.push_back(1);
    }

    if (&input_string[i] == "2")
    {
        return_vector.push_back(2);
    }

    if (&input_string[i] == "3")
    {
        return_vector.push_back(3);
    }

    if (&input_string[i] == "4")
    {
        return_vector.push_back(4);
    }

    if (&input_string[i] == "5")
    {
        return_vector.push_back(5);
    }

    if (&input_string[i] == "6")
    {
        return_vector.push_back(6);
    }

    if (&input_string[i] == "7")
    {
        std::cout << 7 << std::endl;
        return_vector.push_back(7);
    }

    if (&input_string[i] == "8")
    {
        return_vector.push_back(8);
    }

    if (&input_string[i] == "9")
    {
        return_vector.push_back(9);
    }




}

std::cout << "processing string" << std::endl;


for (int j = 0; j<1000; j++)
{
    std::cout << return_vector[j] << std::endl;
}

std::getchar();
return 0;
}

Answer 1

要比较字符串中的字符，请使用

input_string[i] == '0'

所以替换

if (&input_string[i] == "0")

与

if (input_string[i] == '0')  //Removed & from &input_string[i], and replace double quotation(") to single quotation(').

更好的方法

你不需要大量的 if-else，你可以使用 like

return_vector.reserve(input_string.length());  //Requests  vector capacity be at least enough to contain input_string.length() number of element, which reduce redundant reallocation.

for (int i = 0; i<input_string.length(); i++)
{
    return_vector.push_back(input_string[i]-'0');
}

Answer 2

我们可以使用std::transform and a lambda来做到这一点

std::string test = "123456789";
std::vector<int> result(test.size());
std::transform(test.begin(), test.end(), result.begin(), [](char ch) { return ch - '0'; });

Live Example

Answer 3

您可以在 ASCII 字符代码和数字之间进行数学转换 - 只需减去“0”（十进制为 48）：

for (char c : input_string)
    return_vector.push_back(c - '0');

Answer 4

试试这个：

   std::vector<int> toVector(std::string str)
    {
        std::vector<int> result(str.size());
        std::transform(str.begin(), str.end(), result.begin(), [](char ch){return ch-'0';});
        return result;
    }

将数字字符串中的数字转换为整数，然后转换为数组

Convert digits from string of numbers into ints then into array

c++

string

int

vector

char