std::vector 如何對陣列進行assign 和 push_back操作。
阿新 • • 發佈:2019-01-04
1) assign
char arr[] = { 1,2,3 };
std::vector<char> buffer;
buffer.clear();
buffer.insert(buffer.begin(), std::begin(arr), std::end(arr));
assert(buffer.size() == 3);
assert(buffer[0] == 1);
assert(buffer[1] == 2);
assert(buffer[2] == 3);
或者
char arr[] = { 101, 1,2,3 }; std::vector<char> buffer(100, 100); buffer.assign(std::begin(arr), std::end(arr)); assert(buffer.size() == 4); assert(buffer[0] == 101); assert(buffer[1] == 1); assert(buffer[2] == 2); assert(buffer[3] == 3);
或者
char arr[] = { 101, 1,2,3 }; std::vector<char> buffer(arr, arr + sizeof(arr)/sizeof(arr[0])); assert(buffer.size() == 4); assert(buffer[0] == 101); assert(buffer[1] == 1); assert(buffer[2] == 2); assert(buffer[3] == 3);
如果只賦值陣列的一部分:
char arr[] = { 101, 1,2,3 }; std::vector<char> buffer(arr, arr + 2); assert(buffer.size() == 2); assert(buffer[0] == 101); assert(buffer[1] == 1);
或者
char arr[] = { 101, 1,2,3 };
std::vector<char> buffer(std::begin(arr), std::begin(arr) + 2);
assert(buffer.size() == 2);
assert(buffer[0] == 101);
assert(buffer[1] == 1);
2) push_back
char arr[] = { 1,2,3 }; std::vector<char> buffer(1, 100); buffer.insert(buffer.cend(), std::cbegin(arr), std::cend(arr)); assert(buffer.size() == 4); assert(buffer[0] == 100); assert(buffer[1] == 1); assert(buffer[2] == 2); assert(buffer[3] == 3);
如果只賦值陣列的一部分:
char arr[] = { 1,2,3 };
std::vector<char> buffer(1, 100);
buffer.insert(buffer.cend(), std::cbegin(arr), std::cbegin(arr) + 1);
assert(buffer.size() == 2);
assert(buffer[0] == 100);
assert(buffer[1] == 1);