c 语言pop()函数,C --- pop（）函数中的堆栈
如果你用c编写，有一种通用的编程方法。下面是一个示例如下： 头
typedef void *ElementAddr;
typedef void (*PfCbFree)(ElementAddr);
typedef struct StackRecord
{
ElementAddr *array;
int elemsize;
int loglength;
int alloclength;
PfCbFree freefn;
} *Stack;
/* Create a new stack */
Stack stack_create(int elemsize, PfCbFree freefn);
/* Dispose the stack */
void stack_dispose(Stack stk);
/* Make the given stack empty */
void stack_make_empty(Stack stk);
/* Return true if the stack is empty */
int stack_is_empty(Stack stk);
/* Insert a new element onto stack */
void stack_push(Stack stk, ElementAddr elemaddr);
/* Delete the top element off the stack */
void stack_pop(Stack stk);
/* Fetch the top element from the stack */
void stack_top(Stack stk, ElementAddr elemaddr);
/* Fetch & Delete the top element from the stack */
void stack_top_and_pop(Stack stk, ElementAddr elemaddr);
的.cpp
#define MIN_STACK_SIZE (4)
/* Create a new stack */
Stack
stack_create(int elemsize, PfCbFree freefn)
{
Stack stk;
stk = malloc(sizeof(struct StackRecord));
if (stk == NULL) {
fprintf(stderr, "Out of memory\n");
exit(1);
}
stk->array = malloc(elemsize * MIN_STACK_SIZE);
if (stk->array == NULL) {
fprintf(stderr, "Out of memory\n");
exit(1);
}
stk->elemsize = elemsize;
stk->loglength = 0;
stk->alloclength = MIN_STACK_SIZE;
}
/* Dispose the stack*/
void
stack_dispose(Stack stk)
{
stack_make_empty(stk);
free(stk->array);
free(stk);
}
/* Make the given stack empty*/
void
stack_make_empty(Stack stk)
{
if (stk->freefn) {
int i;
for (i = 0; i < stk->loglength; ++i) {
stk->freefn((char *)stk->array +
i * stk->elemsize);
}
}
stk->loglength = 0;
}
/* Return true if the stack is empty*/
int
stack_is_empty(Stack stk)
{
return stk->loglength == 0;
}
static void
stack_grow(Stack stk)
{
stk->alloclength *= 2;
stk->array = realloc(stk->array,
stk->alloclength * stk->elemsize);
}
/* Insert a new element onto stack */
void
stack_push(Stack stk, ElementAddr elemaddr)
{
ElementAddr target;
if (stk->loglength == stk->alloclength)
stack_grow(stk);
target = (char *)stk->array + stk->loglength * stk->elemsize;
memcpy(target, elemaddr, stk->elemsize);
stk->loglength++;
}
/* Delete the top element off the stack */
void
stack_pop(Stack stk)
{
ElementAddr target;
if (stack_is_empty(stk)) {
fprintf(stderr, "Empty stack\n");
exit(1);
}
if (stk->freefn) {
target = (char *)stk->array +
(stk->loglength-1) * stk->elemsize;
stk->freefn(target);
}
stk->loglength--;
}
/* Fetch the top element from the stack */
void
stack_top(Stack stk, ElementAddr elemaddr)
{
void *target = (char *)stk->array +
(stk->loglength-1) * stk->elemsize;
memcpy(elemaddr, target, stk->elemsize);
}
/* Fetch & Delete the top element from the stack */
void
stack_top_and_pop(Stack stk, ElementAddr elemaddr)
{
ElementAddr target;
if (stack_is_empty(stk)) {
fprintf(stderr, "Empty stack\n");
exit(1);
}
target = (char *)stk->array +
(stk->loglength-1) * stk->elemsize;
memcpy(elemaddr, target, stk->elemsize);
stk->loglength--;
}
您可以将其用于任何数据类型。这里是一个测试代码
#include
#include
#include
#include "generic-stack.h"
void strfreefn(ElementAddr elemaddr)
{
free(*(char **)elemaddr);
}
int
main(int argc, char **argv)
{
Stack int_stk, str_stk;
int i;
char *names[] = {
"C", "C++", "Jave", "C#", "Python",
"PHP", "Basic", "Objective C", "Matlab", "Golang"
};
/* test integer stack */
printf("Test integer stack\n");
int_stk = stack_create(sizeof(int), NULL);
for (i = 0; i < 10; ++i) {
stack_push(int_stk, &i);
}
while (!stack_is_empty(int_stk)) {
int val;
stack_top_and_pop(int_stk, &val);
printf("%d\n", val);
}
stack_dispose(int_stk);
/* test string stack */
printf("Test string stack\n");
str_stk = stack_create(sizeof(char *), strfreefn);
for (i = 0; i < 10; ++i) {
char *copy = strdup(names[i]);
char *dest;
stack_push(str_stk, ©);
}
while (!stack_is_empty(str_stk)) {
char *dest;
stack_top_and_pop(str_stk, &dest);
printf("%s\n", dest);
free(dest);
}
stack_dispose(str_stk);
return 0;
}