我想制作一系列词语：＆＃34; Tom＆＃34;，＆＃34; Mike＆＃34;，＆＃34; Tamara＆＃34;，＆＃34; Nik＆＃34;。 ..我想让用户可以输入例如3号，然后随机返回长度为3的单词，这样就可以了（＆＃34; Tom＆＃34;或＆＃34; Nik＆ ＃34）。我认为这是通过指针完成的，但我不知道如何。单词应根据其长度存储在不同的数组中。并且使用指针，您将指向每个阵列（＆＃34; Tom＆＃34;，＆＃34; Nik＆＃34;在同一阵列＆＃34; Tamara＆＃34;在不同阵列和＆＃34; Mike＆＃34;在不同的数组等等......因为它们的长度不一样）。有人可以帮忙吗？
#include<iostream>
#include <string>
using namespace std;
void IzpisPolja(char **polje,int velikost){
int tab[100];
for (int i=0; i<velikost; i++) {
cout<<polje[i]<<endl;
char *zacasni;
tab[i] = strlen(polje[i]);
// cout<<tab[i]<<endl;
}
}
int main(){
const int size = 4;
char* tabelaOseb[size] = {"Tom", "Mike","Tamara","Nik"};
IzpisPolja(tabelaOseb,size);
return 0;
}
答案 0 :(得分：0)
你想有效地做吗？将它们存储在单独的阵列中会增加搜索时间，但也会增加插入，删除的复杂性。
否则，您只需计算数组中n个长度字的实例数，然后生成随机数并返回i个。{/ p>
同时建议使用std::vector
const string* getRandNameOfLength(const string* arr,
const int arrlen,
const int length)
{
int num = 0, j, i;
// Counting number of such names
for (i = 0; i < arrlen; ++i)
{
if (arr[i].size() == length)
num++;
}
// No such name found
if (num == 0)
return NULL;
j = rand() % num;
// Returning random entry of given length
for (i = 0; i < arrlen; ++i)
{
if (arr[i].size() == length && j-- == 0)
return &arr[i];
}
// Function shouldn't get here
return NULL;
}
答案 1 :(得分：0)
#include <iostream>
#include <vector>
#include <cstring>
#include <ctime>
#include <cstdlib>
using namespace std;
const char* return_rand_name(const char** names, size_t length)
{
std::vector<size_t> indexes;
for(int i=0; names[i][0] != 0; ++i)
if(strlen(names[i]) == length)
indexes.push_back(i);
if(indexes.size()==0)
return NULL;
return names[indexes[rand()%indexes.size()]];
}
int main()
{
srand(time(NULL));
const char* names[] = {"Alex","Tom","Annie","Steve","Jesus","Leo","Jerry",""};
std::cout << return_rand_name(names, 3) << std::endl;
return 0;
}
如果您想使用strlen等功能，请添加<cstring>，而不是<string>（其中包含类模板std::string（您应该在C ++中使用） char *）））
答案 2 :(得分：0)
当然，您可以使用原始指针来执行任务，但您也可以开始使用语言（引用，迭代器和智能指针）和C ++标准库可以提供的许多更安全的工具。
我将向您展示一个完整的程序，可以使用上传者（std::map，std::lower_bound）和算法（如main()）来完成您的工作，这些算法可以真正简化您的工作一旦理解。
请注意，作为一种学习练习（对于我们两个人来说），我已经使用了很多＆＃34; new＆＃34;尽我所能，即使可能没有必要或方便。阅读评论以便更好地理解。
单词在课堂中存储和管理，而与用户的互动则在#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <limits>
#include <algorithm>
#include <random> // for mt19937, uniform_int_distribution
#include <chrono> // for high_resolution_clock
size_t random_index( size_t a, size_t b ) {
// Initialize Random Number Generator Engine as a static variable. - Since c++11, You can use those instead of old srand(time(NULL))
static std::mt19937 eng{static_cast<long unsigned int>(std::chrono::high_resolution_clock::now().time_since_epoch().count())};
// use the RNG to generate random numbers uniformly distributed in a range
return std::uniform_int_distribution<size_t>(a,b)(eng);
}
using svs_t = std::vector< std::string >; // I store the words with equal length in a std::vector of std::string
// like typedef, I'll use svs_t instead of std::vector<std::string>
auto string_less_then = [] (const std::string & a, const std::string & b) -> bool { return a.compare(b) < 0; };
// A lambda function is a mechanism for specifying a function object, its primary use is to specify a simple
// action to be performed by some function. I'll use it to compare two string and return true only if a<b
class word_table {
std::map< size_t, svs_t > words; // std::map store elements formed by a combination of a key value and a mapped value, sorted by key
// I'll use word's length as a key for svs_t values
public:
word_table() {}
word_table( std::initializer_list<std::string> vs ) {
insert_words(vs);
}
void insert_words( svs_t vs ) {
for ( auto && s : vs ) add_word(s); // loop for each value in vs, "auto" let the compiler infer the right type of the variable
}
bool add_word( std::string s ) { // I choose to keep the vector sorted and with unique elements
size_t sl = s.length();
if ( sl > 0 ) {
auto & v = words[sl]; // If sl doesn't match the key of any element in the map, a new element is created
// lower_bound return an iterator that poins to the first element in range (begin,end)
auto it = std::lower_bound(v.begin(), v.end(), s, string_less_then); // which does not compare less than s
// I pass the compare function as a lambda
if ( it != v.end() && it->compare(s) == 0 ) return false; // Already present, duplicates not allowed
v.insert(it, s); // Not the most efficient way, but you seem focused on the random access part
return true;
}
return false;
}
bool remove_word( std::string s) {
size_t sl = s.length();
if ( sl > 0 ) {
auto itvw = words.find(sl); // first find the right element in the map, using the string length as a key, but if word is found
if ( itvw == words.end() ) return false; // an iterator to the element following the last element of the container is returned
auto & v = itvw->second; // In a map the elements are stored in pairs, first is the key, second the value
auto it = std::lower_bound(v.begin(), v.end(), s, string_less_then);
if ( it != v.end() && it->compare(s) == 0 ) {
v.erase(it);
if ( v.empty() ) words.erase(itvw);
return true;
}
}
return false;
}
std::string get_random_word( size_t length ) {
if ( length == 0 ) return "";
auto itvw = words.find(length);
if ( itvw == words.end() || itvw->second.empty() ) return "";
return itvw->second[random_index(0, itvw->second.size() - 1)];
}
void show_all() {
for ( auto && i : words ) {
std::cout << " ";
for (auto && w : i.second ) {
std::cout << w << ' ';
}
std::cout << '\n';
}
}
};
constexpr size_t ss_max = std::numeric_limits<std::streamsize>::max();
namespace opt {
enum options { wrong = -1, exit, show, random, add, remove, menu };
}
class menu {
std::map<int,std::string> opts;
public:
menu( std::initializer_list<std::pair<int,std::string>> il ) {
for ( auto && i : il ) opts.insert(i);
}
void show() {
std::cout << "\nYou can choose among these options:\n\n";
for ( auto && i : opts ) {
std::cout << " " << i.first << ". " << i.second << ".\n";
}
}
};
int main()
{
word_table names({"Tom", "Mike","Tamara","Robert","Lenny","Nick","Alex","Sue","Irina","Beth","Anastacia","Bo"});
int choise = opt::exit;
menu menu_options { {opt::exit, "Exit program"}, {opt::show, "Show all stored names"},
{opt::random, "Show a random name"}, {opt::add, "Add a new name"},
{opt::remove, "Remove a name"} };
menu_options.show();
do {
std::cout << "\nPlease, enter a number (" << opt::menu << " to show again all options): ";
std::cin >> choise;
if ( std::cin.fail() ) { // the user enter something that is not a number
choise = opt::wrong;
std::cin.clear();
std::cin.ignore(ss_max,'\n');
}
if ( std::cin.eof() ) break; // use only if you are redirecting input from file
std::string str;
switch ( choise ) {
case opt::exit:
std::cout << "\nYou choose to quit, goodbye.\n";
break;
case opt::show:
std::cout << "\nAll the stored names, classified by word\'s length:\n\n";
names.show_all();
break;
case opt::random:
size_t l;
std::cout << "Please, enter the length of the name: ";
std::cin >> l;
if ( std::cin.good() ) {
std::string rs = names.get_random_word(l);
if ( rs == "" ) {
std::cout << "\nNo name of length " << l << " has been found.\n";
} else {
std::cout << "\n " << rs << '\n';
}
}
break;
case opt::add:
std::cout << "Please, enter the name You want to add: ";
std::cin >> str; // read a string from cin, you can write more than a word (separeted by spaces)
std::cin.ignore(ss_max,'\n'); // but only the first is stored
if ( names.add_word(str) ) {
std::cout << "\n The name " << str << " has been successfully added.\n";
} else {
std::cout << "\n No name has been added";
if ( str != "" ) std::cout << ", "<< str << " is already present.\n";
else std::cout << ".\n";
}
break;
case opt::remove:
std::cout << "Please, enter the name You want to remove: ";
std::cin >> str;
if ( names.remove_word(str) ) {
std::cout << "\n " << str << " has been succesfully removed.\n";
} else {
std::cout << "\n No name has been removed";
if ( str != "" ) std::cout << ", " << str << " wasn't found.\n";
else std::cout << ".\n";
}
break;
case opt::menu:
menu_options.show();
break;
default:
std::cout << "\n Sorry, that's not an option.\n";
}
} while ( choise != opt::exit );
return 0;
}
中执行。
<form id="loginForm" name="loginForm" ng-submit="submitForm()">
<div class="form-group">
<input type="text" class="form-control" id="userCompany" placeholder="Company" ng-model="user.companyId" required>
</div>
<div class="form-group">
<input type="text" class="form-control" id="userUsername" placeholder="Username" ng-model="user.userId" required>
</div>
<div class="form-group">
<input type="password" class="form-control" id="userPassword" placeholder="Password" ng-model="user.password" required>
</div>
<button type="submit" class="btn btn-default">Submit</button>
<button class="btn btn-default">Change Password</button>
<span ng-show="errorData">{{errorData}}</span>
</form>
我希望它可以提供帮助。