C++ 如何将字符串中的字符推送到二维向量中
我有一根弦s=如果人注定要留在地面上,上帝会给我们根 我去掉了空间,让Ifman留在地面上,上帝会给我根 现在我想把字符串的字符放入一个7行8列的2d向量中。 输出应该如下所示:C++ 如何将字符串中的字符推送到二维向量中,c++,vector,data-structures,2d-vector,C++,Vector,Data Structures,2d Vector,我有一根弦s=如果人注定要留在地面上,上帝会给我们根 我去掉了空间,让Ifman留在地面上,上帝会给我根 现在我想把字符串的字符放入一个7行8列的2d向量中。 输出应该如下所示: ifmanwas meanttos tayonthe groundgo dwouldha vegivenu sroots 我尝试了下面的方法,但不起作用 void encryption(string s) { const int rows = 7; const int colums = 8
ifmanwas
meanttos
tayonthe
groundgo
dwouldha
vegivenu
sroots
我尝试了下面的方法,但不起作用
void encryption(string s)
{
const int rows = 7;
const int colums = 8;
vector<vector<char>> v;
for (int i = 0; i < rows; i++)
{
vector<char>temp;
for (int j = 0; i < colums; j++)
{
temp.push_back(s[0]);
s.erase(0);
}
v.push_back(temp);
}
for (int i = 0; i < v.size(); i++)
{
for (int j = 0; j < v[i].size(); j++)
cout << v[i][j];
}
}
您的代码有几个问题: 此处循环中使用了1个错误的索引变量: 对于int j=0;i
#include <string>
#include <vector>
#include <iostream>
using namespace std;
void encryption(string s)
{
const int rows = 7;
const int colums = 8;
vector<vector<char>> v;
for (int i = 0; i < rows; i++)
{
vector<char>temp;
for (int j = 0; j < colums && !s.empty(); j++) // <-- Note we stop the loop if the string is empty.
{
temp.push_back(s[0]);
s.erase(s.begin()); // <-- This erases the first character
}
v.push_back(temp);
}
for (size_t i = 0; i < v.size(); i++)
{
for (size_t j = 0; j < v[i].size(); j++)
cout << v[i][j];
cout << "\n"; // <-- You are missing this in your output
}
}
int main()
{
encryption("ifmanwasmeanttostayonthegroundgodwouldhavegivenusroots");
}
鉴于此,这是一个非常低效的方法,因为您正在擦除字符串的第一个字符。没有必要为此删除字符
下面是一个使用std::vector的替代解决方案,以及一个while循环,用于跟踪字符串中的开始和结束迭代器:
#include <string>
#include <vector>
#include <algorithm>
#include <iostream>
void encryption(std::string s)
{
const size_t columns = 8;
std::vector<std::string> v;
// start at beginning of string
auto startIter = s.begin();
// point to either 8 characters after the start, or the end of the
// string, whichever comes first
auto endIter = startIter + std::min(columns, static_cast<size_t>(std::distance(startIter, s.end())));
while (true)
{
// just push on a string using the start and end iterators
v.push_back({startIter, endIter});
// if the end iterator is at the end of the string, quit
if (endIter == s.end())
break;
// move the start to the end
startIter = endIter;
// move the end to either 8 characters after the start, or the
// end of the string, whichever comes first
endIter = startIter + std::min(columns, static_cast<size_t>(std::distance(startIter, s.end())));
}
// Output the results
for (auto& vrow : v)
std::cout << vrow << "\n";
}
int main()
{
encryption("ifmanwasmeanttostayonthegroundgodwouldhavegivenusroots");
}
强烈建议检查字符串是否已用完。s.erase0;-为什么要删除字符?根据问题描述,删除字符的原因是什么?这只是将一系列字符复制到循环中的另一个缓冲区中,并指定和更新起始和结束索引/迭代器。不需要擦除。请解释你所说的不工作是什么意思为什么是向量?为什么不是向量?那么你就不会一次处理一个角色了。为什么限制为7行?如果字符串很短,或者字符串的跨度超过7行,该怎么办;i
#include <string>
#include <vector>
#include <algorithm>
#include <iostream>
void encryption(std::string s)
{
const size_t columns = 8;
std::vector<std::string> v;
// start at beginning of string
auto startIter = s.begin();
// point to either 8 characters after the start, or the end of the
// string, whichever comes first
auto endIter = startIter + std::min(columns, static_cast<size_t>(std::distance(startIter, s.end())));
while (true)
{
// just push on a string using the start and end iterators
v.push_back({startIter, endIter});
// if the end iterator is at the end of the string, quit
if (endIter == s.end())
break;
// move the start to the end
startIter = endIter;
// move the end to either 8 characters after the start, or the
// end of the string, whichever comes first
endIter = startIter + std::min(columns, static_cast<size_t>(std::distance(startIter, s.end())));
}
// Output the results
for (auto& vrow : v)
std::cout << vrow << "\n";
}
int main()
{
encryption("ifmanwasmeanttostayonthegroundgodwouldhavegivenusroots");
}
ifmanwas
meanttos
tayonthe
groundgo
dwouldha
vegivenu
sroots