我想创建一个随机字符串,由字母-数字字符组成。我希望能够指定字符串的长度。
如何在c++中做到这一点?
我想创建一个随机字符串,由字母-数字字符组成。我希望能够指定字符串的长度。
如何在c++中做到这一点?
当前回答
随机字符串,每个运行文件=不同的字符串
auto randchar = []() -> char
{
const char charset[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz";
const size_t max_index = (sizeof(charset) - 1);
return charset[randomGenerator(0, max_index)];
};
std::string custom_string;
size_t LENGTH_NAME = 6 // length of name
generate_n(custom_string.begin(), LENGTH_NAME, randchar);
其他回答
Qt使用示例:
QString random_string(int length=32, QString allow_symbols=QString("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")) {
QString result;
qsrand(QTime::currentTime().msec());
for (int i = 0; i < length; ++i) {
result.append(allow_symbols.at(qrand() % (allow_symbols.length())));
}
return result;
}
我刚刚测试了这个,它工作得很好,不需要查找表。Rand_alnum()在某种程度上强制输出字母数字,但因为它从可能的256个字符中选择62个,所以这不是什么大问题。
#include <cstdlib> // for rand()
#include <cctype> // for isalnum()
#include <algorithm> // for back_inserter
#include <string>
char
rand_alnum()
{
char c;
while (!std::isalnum(c = static_cast<char>(std::rand())))
;
return c;
}
std::string
rand_alnum_str (std::string::size_type sz)
{
std::string s;
s.reserve (sz);
generate_n (std::back_inserter(s), sz, rand_alnum);
return s;
}
Mehrdad Afshari的回答可以解决这个问题,但我觉得对于这个简单的任务来说,它有点太啰嗦了。查询表有时可以创造奇迹:
#include <ctime>
#include <iostream>
#include <unistd.h>
std::string gen_random(const int len) {
static const char alphanum[] =
"0123456789"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz";
std::string tmp_s;
tmp_s.reserve(len);
for (int i = 0; i < len; ++i) {
tmp_s += alphanum[rand() % (sizeof(alphanum) - 1)];
}
return tmp_s;
}
int main(int argc, char *argv[]) {
srand((unsigned)time(NULL) * getpid());
std::cout << gen_random(12) << "\n";
return 0;
}
注意rand生成的随机数质量很差。
//C++ Simple Code
#include <bits/stdc++.h>
using namespace std;
int main() {
vector<char> alphanum =
{'0','1','2','3','4',
'5','6','7','8','9',
'A','B','C','D','E','F',
'G','H','I','J','K',
'L','M','N','O','P',
'Q','R','S','T','U',
'V','W','X','Y','Z',
'a','b','c','d','e','f',
'g','h','i','j','k',
'l','m','n','o','p',
'q','r','s','t','u',
'v','w','x','y','z'
};
string s="";
int len=5;
srand(time(0));
for (int i = 0; i <len; i++) {
int t=alphanum.size()-1;
int idx=rand()%t;
s+= alphanum[idx];
}
cout<<s<<" ";
return 0;
}
void gen_random(char *s, size_t len) {
for (size_t i = 0; i < len; ++i) {
int randomChar = rand()%(26+26+10);
if (randomChar < 26)
s[i] = 'a' + randomChar;
else if (randomChar < 26+26)
s[i] = 'A' + randomChar - 26;
else
s[i] = '0' + randomChar - 26 - 26;
}
s[len] = 0;
}