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69 lines
1.6 KiB
C++
69 lines
1.6 KiB
C++
// how to convert std::vector<std::string> to const char**?
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#include <string.h>
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#include <iostream>
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#include <string>
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#include <vector>
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void print_strings(const std::vector<std::string> strings) {
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using std::cout;
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using std::endl;
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cout << "== Printing some std::vector<std::string> strings:" << endl;
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for (const std::string &s : strings) {
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cout << s << endl;
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}
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}
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const char** convert_to_c(const std::vector<std::string> strings) {
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// Note: perfectly fine to "new" const char*.
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const char** strings_c = new const char*[strings.size()+1];
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for (size_t i = 0; i < strings.size(); ++i) {
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// XXX No need to copy the string here.
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char* string_c = new char[strings.at(i).size()+1];
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strncpy(string_c, strings.at(i).c_str(), strings.at(i).size()+1);
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strings_c[i] = string_c;
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}
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strings_c[strings.size()] = NULL;
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return strings_c;
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}
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void free_c(const char** strings_c) {
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for (size_t i = 0; strings_c[i] != NULL; ++i) {
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delete[] strings_c[i];
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}
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delete[] strings_c;
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}
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void print_strings_c(const char** strings_c) {
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using std::cout;
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using std::endl;
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cout << "== Printing some const char** strings:" << endl;
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for (size_t i = 0; strings_c[i] != NULL; ++i) {
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cout << strings_c[i] << endl;
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}
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}
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void foo(const char* string) {
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printf("foo: %s\n", string);
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}
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int main() {
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foo("foo");
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char* bar = new char[4];
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strncpy(bar, "bar", 4);
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foo(bar);
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delete[] bar;
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std::vector<std::string> some_strings = { "just", "some", "strings", "here" };
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print_strings(some_strings);
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const char **some_strings_c = convert_to_c(some_strings);
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print_strings_c(some_strings_c);
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free_c(some_strings_c);
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}
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