c - 在 C 中释放多维数组

Question

假设我们有:

void createMultiArray(){
    int i,j;
    char*** codes = malloc(5 * sizeof(char**));
    for ( i = 0; i <= 4; i++ ) {
        codes[i] = malloc((i+1) * sizeof(char*));
        for ( j = 0; j <= i; j++ ) {
            codes[i][j] = malloc(2 * sizeof(char));
        }
   }

我应该如何释放代码？

free(codes);

或

int i,j;
for(i = 0; i <=4; i++){
    for(j = 0; j <= i; j++){
        free(codes[i][j]);
    }
    free(codes[i]);
}
free(codes);

Answer 1

这样想 - 每个 malloc 都应该有一个 free。

// you're allocating memory for codes
// must be freed with free(codes);
char*** codes = malloc(5 * sizeof(char**));

for ( i = 0; i <= 4; i++ ) {

    // allocating memory for every element in codes
    // must be freed with free(codes[i]);
    codes[i] = malloc((i+1) * sizeof(char*));

    for ( j = 0; j <= i; j++ ) {

        // allocating memory for every element in every element in codes
        // must be freed with free(codes[i][j])
        codes[i][j] = malloc(2 * sizeof(char));

    }
}

是的，您的第二个选项是正确的。