You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
65 lines
1.5 KiB
C++
65 lines
1.5 KiB
C++
// how to convert std::vector<std::string> to const char**?
|
|
|
|
#include <string.h>
|
|
|
|
#include <iostream>
|
|
#include <string>
|
|
#include <vector>
|
|
|
|
void print_strings(const std::vector<std::string> strings) {
|
|
using std::cout;
|
|
using std::endl;
|
|
|
|
cout << "== Printing some std::vector<std::string> strings:" << endl;
|
|
for (const std::string &s : strings) {
|
|
cout << s << endl;
|
|
}
|
|
}
|
|
|
|
const char** convert_to_c(const std::vector<std::string> strings) {
|
|
// Note: perfectly fine to "new" const char*.
|
|
const char** strings_c = new const char*[strings.size()+1];
|
|
for (size_t i = 0; i < strings.size(); ++i) {
|
|
// Note: const char** = non-const "array" to const char*, i.e. can modify
|
|
// pointers to the strings but not the strings themselves.
|
|
strings_c[i] = strings.at(i).c_str();
|
|
}
|
|
strings_c[strings.size()] = NULL;
|
|
|
|
return strings_c;
|
|
}
|
|
|
|
void free_c(const char** strings_c) {
|
|
delete[] strings_c;
|
|
}
|
|
|
|
void print_strings_c(const char** strings_c) {
|
|
using std::cout;
|
|
using std::endl;
|
|
|
|
cout << "== Printing some const char** strings:" << endl;
|
|
for (size_t i = 0; strings_c[i] != NULL; ++i) {
|
|
cout << strings_c[i] << endl;
|
|
}
|
|
}
|
|
|
|
void foo(const char* string) {
|
|
printf("foo: %s\n", string);
|
|
}
|
|
|
|
int main() {
|
|
foo("foo");
|
|
char* bar = new char[4];
|
|
strncpy(bar, "bar", 4);
|
|
foo(bar);
|
|
delete[] bar;
|
|
|
|
std::vector<std::string> some_strings = { "just", "some", "strings", "here" };
|
|
print_strings(some_strings);
|
|
|
|
const char **some_strings_c = convert_to_c(some_strings);
|
|
|
|
print_strings_c(some_strings_c);
|
|
free_c(some_strings_c);
|
|
}
|