我正在嘗試解決“假設是”一個簡單的 C 問題。
問：用戶使用 int 指標接收“無限”輸入，直到使用 malloc 和 realloc 接收到 EOF。
我定義了一個這樣的 int 指標：
int *inputBuffer = NULL;
并使用此方法對其進行初始化：
/* #define BUFFER_SIZE 8 - already defined at top of code, posted here for more info */
/* Creates buffer by using malloc -
if succeded returns true, otherwise false */
int createBuffer(int **inputBuffer)
{
*inputBuffer = (int*) calloc(BUFFER_SIZE, sizeof(char)); /* Allocate memory to get input from user */
if(*inputBuffer == NULL)
return FALSE;
return TRUE;
}
通過呼叫createBuffer(&inputBuffer)
到目前為止這么好，記憶體分配成功。在開始接收來自用戶的字符之前，我定義了以下屬性：
int totalCharacters = 0;
int bufferExtendsCounter = 1;
int character;
下一步是接收來自用戶的字符輸入，如下所示：
/* #define MEMORY_SAFE_GAP 4 - already defined at top of code, posted here for more info */
while((character = getchar()) != EOF && inputBuffer != NULL)
{
/* Check if reallocate needs to be called since almost maxed out buffer */
if(totalCharacters - MEMORY_SAFE_GAP > (BUFFER_SIZE * bufferExtendsCounter))
{
/* Add 1 to extends buffer times */
bufferExtendsCounter =1;
if(!extendBuffer(&inputBuffer, totalCharacters))
printf("\nFailed to allocate more memory.");
}
/* Initialize buffer with character, this is safe since there is a memory safe gap */
inputBuffer[totalCharacters] = character;
totalCharacters ;
}
擴展緩沖區如下所示：
/* Extends buffer size by using realloc
if succeded returns true, otherwise false */
int extendBuffer(int **inputBuffer, int minimumBufferSize)
{
/* Check how many times buffer needs to be multiple (at least) */
int multipleBufferNumber = (minimumBufferSize / BUFFER_SIZE) 1;
int newBufferSize = BUFFER_SIZE * multipleBufferNumber * sizeof(char);
while(newBufferSize < minimumBufferSize)
{
multipleBufferNumber =1;
newBufferSize = BUFFER_SIZE * multipleBufferNumber * sizeof(char);
}
/* Reallocate memory for next chunck of data */
*inputBuffer = realloc(*inputBuffer, newBufferSize);
/* Check if memory successfully allocated */
if(*inputBuffer == NULL)
return FALSE;
return TRUE;
}
看起來我擴展了足夠的緩沖區大小以供用戶進行更多輸入，但仍然出現錯誤：
corrupted size vs. prev_size: 0x08f86010 ***
示例輸入：
TestProgramTest (Pressed Enter after last 't')
(DebugPrint: Received 13 characters)
(DebugPrint: Reallocating to size 16)
*** Error in `./test': corrupted size vs. prev_size: 0x08f86010 ***
編輯（由于缺少代碼部分）： 以下部分就在while 回圈之后：
inputBuffer[totalCharacters] = '\0';
printf("\nInput by user:\n");
/* #define LINE_LENGTH 5 - already defined at top of code, posted here for more info */
printBuffer(inputBuffer, LINE_LENGTH, totalCharacters);
/* free memory */
free(inputBuffer);
和 printBuffer 看起來像：
/* Prints the buffer data to pretty output */
void printBuffer(int *inputBuffer, int lineLength, int totalCharacters)
{
int i;
for(i = 0; i < totalCharacters; i )
{
/* Print each char value */
printf("%c", inputBuffer[i]);
/* Check if got to line limit, if so enter new line */
if((i 1) % lineLength == 0)
printf("\n");
}
}
第二次編輯： 將所有 int 指標部分更改為 char 指標。 完整代碼如下所示：
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#define LINE_LENGTH 5
#define BUFFER_SIZE 8
#define TRUE 1
#define FALSE 0
#define MEMORY_SAFE_GAP 4
int createBuffer(char **inputBuffer);
int extendBuffer(char **inputBuffer, int minimumBufferSize);
void printBuffer(char *inputBuffer, int lineLength, int totalCharacters);
int main(void)
{
char *inputBuffer = NULL;
if(!createBuffer(&inputBuffer))
{
printf("Memory cannot be allocated, program will exit now.");
exit(-1);
}
int totalCharacters = 0;
int bufferExtendsCounter = 1;
char character;
printf("Please enter a string:\n");
/* Loop till EOF received */
while((character = getchar()) != EOF && inputBuffer != NULL)
{
/* Check if reallocate needs to be called since almost maxed out buffer */
if(totalCharacters - MEMORY_SAFE_GAP > (BUFFER_SIZE * bufferExtendsCounter))
{
/* Add 1 to extends buffer times */
bufferExtendsCounter =1;
if(!extendBuffer(&inputBuffer, totalCharacters))
printf("\nFailed to allocate more memory.");
}
/* Initialize buffer with character, this is safe since there is a memory safe gap */
inputBuffer[totalCharacters] = character;
totalCharacters ;
}
inputBuffer[totalCharacters] = '\0';
printBuffer(inputBuffer, LINE_LENGTH, totalCharacters);
/* free memory */
free(inputBuffer);
return 0;
}
/* Creates buffer by using malloc
if succeded returns true, otherwise false */
int createBuffer(char **inputBuffer)
{
/* Allocate memory to get input from user */
*inputBuffer = (char*) calloc(BUFFER_SIZE, sizeof(char));
if(*inputBuffer == NULL)
return FALSE;
return TRUE;
}
/* Extends buffer size by using realloc
if succeded returns true, otherwise false */
int extendBuffer(char **inputBuffer, int minimumBufferSize)
{
/* Check how many times buffer needs to be multiple (at least) */
int multipleBufferNumber = (minimumBufferSize / BUFFER_SIZE) 1;
int newBufferSize = BUFFER_SIZE * multipleBufferNumber * sizeof(char);
while(newBufferSize < minimumBufferSize)
{
multipleBufferNumber =1;
newBufferSize = BUFFER_SIZE * multipleBufferNumber * sizeof(char);
}
/* Reallocate memory for next chunck of data */
*inputBuffer = realloc(*inputBuffer, newBufferSize);
/* Check if memory successfully allocated */
if(*inputBuffer == NULL)
return FALSE;
return TRUE;
}
/* Prints the buffer data to pretty output */
void printBuffer(char *inputBuffer, int lineLength, int totalCharacters)
{
printf("Printing buffer\n");
int i;
for(i = 0; i < totalCharacters; i )
{
/* Print each char value */
printf("%c", inputBuffer[i]);
/* Check if got to line limit, if so enter new line */
if((i 1) % lineLength == 0)
printf("\n");
}
}
任何幫助都會很棒！
提前致謝。
uj5u.com熱心網友回復：
就在這兒
*inputBuffer = (int*) calloc(BUFFER_SIZE, sizeof(char));
您為 8 個字符保留空間，但嘗試在其中存盤 8 個整數
為什么 inputBuffer 不是一個 char*？因為這就是你要存盤的
現在你已經解決了 - 看看這個
if (totalCharacters - MEMORY_SAFE_GAP > (BUFFER_SIZE * bufferExtendsCounter))
我不知道'MEMORY_SAFE_GAP'的意圖是什么，但它是錯誤的
看看當我輸入第 8 個字符時會發生什么
if(8 - 4 > 8 * 1)
是假的，所以你不要擴展緩沖區。
這種“安全間隙”可確保您始終跑到最后，如果您剛剛擁有，您的代碼將不再崩潰
if (totalCharacters >= (BUFFER_SIZE * bufferExtendsCounter))
輸出仍然有點亂碼，但你可能可以解決這個問題。我輸入 1234567890 得到
Please enter a string:
1234567890
^Z
Printing buffer
12345
678═0
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