我创建了一个程序，可以使用强力回溯算法解决C ++中的数独难题，但是在分析了valgrind中的内存使用情况后，我注意到它有一个小泄漏。我知道一个GCC错误，它可以解决1个错过的空闲和72,704个仍可访问的字节。
我似乎错过了903 free() / delete / delete[]次来电，占据了大约100KB的内存。
有谁知道导致内存泄漏的原因以及如何解决？
Backtracker.cpp
#include "Backtracker.h"
/**
* Clears all dynamic memory in the list.
* @param lst: the pointer to the list to be cleared
*/
static void clearList(std::list<Grid*> *lst) {
std::list<Grid*>::iterator it;
for (unsigned int i = 0; i < lst->size(); i++) {
it = lst->begin();
std::advance(it, i);
delete *it;
}
delete lst;
}
/**
* Solves the sudoku puzzle or returns a null if there is no solution.
* @param g: a pointer to the starting grid
* @return: a pointer to the solution
*/
Grid* solve(Grid *g) {
if (g->isGoal()) {
return g;
}
std::list<Grid*> *successors = g->getSuccessors();
std::list<Grid*>::iterator it;
for (unsigned int i = 0; i < successors->size(); i++) {
it = successors->begin();
std::advance(it, i);
if ((*it)->isValid()) {
Grid *solution = solve(*it);
if (solution != nullptr) {
solution = solution->copyGrid();
clearList(successors);
return solution;
}
}
}
clearList(successors);
return nullptr;
}`
Grid.cpp
#include "Grid.h"
/**
* Constructor for the Grid class.
*/
Grid::Grid() {
grid = new int*[SIZE];
for (int i = 0; i < SIZE; i++) {
grid[i] = new int[SIZE];
}
currRow = 0;
currCol = 0;
}
/**
* Destructor for the Grid class.
*/
Grid::~Grid() {
for (int i = 0; i < SIZE; i++) {
delete[] grid[i];
}
delete[] grid;
}
/**
* Getter for any value in the grid.
* @param row: the index of the row
* @param col: the index of the column
* @return: the value at the given row and column indexes
*/
int Grid::getValue(int row, int col) {
return grid[row][col];
}
/**
* Setter for any value in the grid.
* @param row: the index of the row
* @param col: the index of the column
* @param value: the value to set at the given row and column
*/
void Grid::setValue(int row, int col, int value) {
grid[row][col] = value;
}
/**
* Allocates dynamic memory for a new grid and copies over the contents.
* @return: a pointer to the new grid object
*/
Grid* Grid::copyGrid() {
Grid *copy = new Grid();
for (int r = 0; r < SIZE; r++) {
for (int c = 0; c < SIZE; c++) {
copy->setValue(r, c, grid[r][c]);
}
}
copy->currRow = currRow;
copy->currCol = currCol;
return copy;
}
/**
* Creates a list of successors by moving the cursor and setting the next value.
* @return: a list of the successors
*/
std::list<Grid*>* Grid::getSuccessors() {
std::list<Grid*> *successors = new std::list<Grid*>();
if (canMove()) {
Grid *copy = copyGrid();
copy->moveCursor();
if (copy->getValue(currRow, currCol) != 0) {
successors->push_back(copy);
return successors;
} else {
delete copy;
}
for (int i = 0; i < SIZE; i++) {
copy = copyGrid();
copy->moveCursor();
copy->setValue(currRow, currCol, i + 1);
if (copy->isValid()) {
successors->push_back(copy);
} else {
delete copy;
}
}
}
return successors;
}
/**
* Determines if the current configuration could be a possible solution.
* @return: true if it could be a solution, false if not
*/
bool Grid::isValid() {
// Checks each row for a duplicate number.
for (int r = 0; r < SIZE; r++) {
bool nums[SIZE] = {false * SIZE};
for (int c = 0; c < SIZE; c++) {
if ((grid[r][c] > 0) && (!nums[grid[r][c] - 1])) {
nums[grid[r][c] - 1] = true;
} else if ((grid[r][c] > 0) && (nums[grid[r][c] - 1])) {
return false;
}
}
}
// Checks each column for a duplicate number.
for (int c = 0; c < SIZE; c++) {
bool nums[SIZE] = {false * SIZE};
for (int r = 0; r < SIZE; r++) {
if ((grid[r][c] > 0) && (!nums[grid[r][c] - 1])) {
nums[grid[r][c] - 1] = true;
} else if ((grid[r][c] > 0) && (nums[grid[r][c] - 1])) {
return false;
}
}
}
// Checks squares.
int val;
for (int sRow = 0; sRow < SQUARES; sRow++) {
for (int sCol = 0; sCol < SQUARES; sCol++) {
bool nums[SIZE] = {false * SIZE};
for (int r = 0; r < SQUARES; r++) {
for (int c = 0; c < SQUARES; c++) {
val = grid[(sRow * 3) + r][(sCol * 3) + c];
if ((val > 0) && (!nums[val - 1])) {
nums[val - 1] = true;
} else if ((val > 0) && (nums[val - 1])) {
return false;
}
}
}
}
}
return true;
}
/**
* Determines if the current configuration is a solution or not.
* @return: true if it is a solution, false if not
*/
bool Grid::isGoal() {
for (int r = 0; r < SIZE; r++) {
for (int c = 0; c < SIZE; c++) {
if (grid[r][c] <= 0 || grid[r][c] > 9) {
return false;
}
}
}
return isValid();
}
/**
* Determines if the cursor can be advanced a position or not.
* @return: true if the cursor can be moved, false if it is at the last position of the board
*/
bool Grid::canMove() {
return !((currRow == SIZE - 1) && (currCol == SIZE));
}
/**
* Moves the cursor to the next position if it is not at the last position of the board.
* @return: true if the cursor was moved, false if it cannot be moved
*/
bool Grid::moveCursor() {
if (!canMove()) {
return false;
} else {
if (currCol != SIZE - 1) {
currCol++;
return true;
} else {
currCol = 0;
if (currRow == SIZE - 1) {
return false;
} else {
currRow++;
return true;
}
}
}
}
/**
* Creates a string for the given row.
* @param row: the index of the row to generate a string for
* @return: a string for that row
*/
std::string Grid::rowString(int row) {
std::string output = "";
int c;
for (c = 0; c < 3; c++) {
output += std::to_string(grid[row][c]) + " ";
}
output += "| ";
for (c = 3; c < 6; c++) {
output += std::to_string(getValue(row, c)) + " ";
}
output += "| ";
for (c = 6; c < SIZE; c++) {
output += std::to_string(getValue(row, c)) + " ";
}
return output;
}
/**
* Creates a string representation of the entire grid.
* @return: a string for the entire grid.
*/
std::string Grid::toString() {
std::string output = "";
// TODO remove this
output += std::to_string(currRow) + "," + std::to_string(currCol) + "\n";
int r;
for (r = 0; r < 3; r++) {
output += rowString(r) + "\n";
}
output += "---------------------\n";
for (r = 3; r < 6; r++) {
output += rowString(r) + "\n";
}
output += "---------------------\n";
for (r = 6; r < SIZE; r++) {
output += rowString(r) + "\n";
}
return output;
}`
valgrind输出
==3021==
==3021== HEAP SUMMARY:
==3021== in use at exit: 106,488 bytes in 903 blocks
==3021== total heap usage: 3,260,824 allocs, 3,259,921 frees, 121,174,996 bytes allocated
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 19 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x401A69: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 20 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 21 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 22 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 23 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 24 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 25 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 26 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 27 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 412 (16 direct, 396 indirect) bytes in 1 blocks are definitely lost in loss record 28 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x40230F: main (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== 29,664 (1,152 direct, 28,512 indirect) bytes in 72 blocks are definitely lost in loss record 31 of 32
==3021== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3021== by 0x402620: Grid::copyGrid() (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x404104: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021== by 0x4040ED: solve(Grid*) (in /home/anthony/Documents/Code/c-c++-projects/Sudoku-Solver/sudoku-solver)
==3021==
==3021== LEAK SUMMARY:
==3021== definitely lost: 1,312 bytes in 82 blocks
==3021== indirectly lost: 32,472 bytes in 820 blocks
==3021== possibly lost: 0 bytes in 0 blocks
==3021== still reachable: 72,704 bytes in 1 blocks
==3021== suppressed: 0 bytes in 0 blocks
==3021== Reachable blocks (those to which a pointer was found) are not shown.
==3021== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==3021==
==3021== For counts of detected and suppressed errors, rerun with: -v
==3021== ERROR SUMMARY: 11 errors from 11 contexts (suppressed: 0 from 0)
答案 0 :(得分：1)
不确定这是你的问题，但是...根据valgrind，问题与Grid::copyGrid()中分配的内存有关，所以由以下new分配的内存
Grid* Grid::copyGrid() {
Grid *copy = new Grid();
// ...
return copy;
}
我怀疑问题（问题？）在solve()。
if ((*it)->isValid()) {
Grid *solution = solve(*it);
if (solution != nullptr) {
solution = solution->copyGrid();
clearList(successors);
return solution;
}
}
观察solve()返回
solution
solution = solution->copyGrid();
所以分配的（new）值却丢失了
solution的原始值
Grid *solution = solve(*it);
来自solve()，因此已分配。
我的意思是：删除solve()返回的值？
我想你应该写点像
if ((*it)->isValid()) {
Grid *solution = solve(*it);
if (solution != nullptr) {
Grid *retSol = solution->copyGrid();
clearList(successors);
delete solution;
return retSol;
}
}
- 编辑 -
OP答案：
我刚试过这个，但它只会导致分段错误。删除删除解决方案; line修复了分段错误，但内存泄漏仍然存在。
我明白了......
这里的问题是（如果我没错），solve()也可以返回收到的值
Grid* solve(Grid *g) {
if (g->isGoal()) {
return g;
}
... Uhmmm
因此，如果与*it不同，则必须将 删除。
我不喜欢它，但我建议
if ((*it)->isValid()) {
Grid *solution = solve(*it);
if (solution != nullptr) {
Grid *retSol = solution->copyGrid();
clearList(successors);
if ( solution != *it )
delete solution;
return retSol;
}
}