[英]segmentation fault when trying to allocate memory for a string in a struct
Working on a problem where I have to read data from a file into a struct. 解决必须将文件中的数据读取到结构中的问题。
The file is organized so that there is a name, a few lines of ASCII art terminated by a # and a rating. 该文件经过组织,以便有一个名称,几行ASCII图片(以#结尾)和一个等级。 Here is an example
这是一个例子
Sample Name
( S )
( S )
# 5
I have my struct set up like this: 我有这样的结构设置:
typedef struct
{
char* name;
char* art;
int rating;
}CASE;
My problem is that I keep getting a segmentation fault
when I try to dynamically allocate memory for the name string in the code below: 我的问题是,当我尝试为以下代码中的名称字符串动态分配内存时,我始终遇到
segmentation fault
:
/*FPin is file pointer to the txt file and all is the array of structs*/
void readFile(FILE* FPin, CASE** all)
{
CASE* walker = *all;
int count = 0;
char buffer[160];
char* bufferPtr = buffer;
char nameBuffer[100];
/*Reads in the name*/
while(fscanf(FPin, "%[^\n]", nameBuffer))
{
printf("string is %s\n", nameBuffer);
walker->name = (char*)malloc(sizeof(char)*(strlen(nameBuffer+1))); /*ERROR*/
strcpy(walker->name, nameBuffer);
}
return;
}
I made a note of where I believe the error to be in the code above because once I added that line, I started getting it. 我记下了我认为上面代码中的错误的位置,因为一旦添加了该行,便开始获取它。
I'm basically reading a name from a text into a nameBuffer (array) and then using strcpy to copy this name into the struct. 我基本上是从文本中读取一个名称到nameBuffer(数组)中,然后使用strcpy将此名称复制到该结构中。 Any advice on how to fix this?
有关如何解决此问题的任何建议?
Thanks for looking. 感谢您的光临。
I'll include the rest of my source below: 我将在下面包括我的其余资料:
int main (void)
{
CASE* all;
FILE* FPin;
if((FPin = fopen("art.txt", "r")) == NULL)
{
printf("Error opening file.");
exit(100);
}
allocateStructMem(&all);
readFile(FPin, &all);
fclose(FPin);
return 0;
}
void allocateStructMem (CASE** all)
{
if((*all = (CASE*)malloc(sizeof(CASE)*1000)) == NULL)
{
printf("Fatal memory error!\n");
exit(1);
}
return;
}
strlen(nameBuffer+1)
strlen(nameBuffer + 1)
strlen(nameBuffer)+1
You also have to do something like this when you malloc all
: 当您
all
分配时,还必须执行以下操作:
int allocateStructMem(CASE **all)
{
/* +----- Note. And no need to cast as malloc returns (void *)
| */
if((*all = malloc(sizeof(CASE*) * 1000)) == NULL)
To prevent overflow you have to limit the length of fscanf
, ie: 为了防止溢出,您必须限制
fscanf
的长度,即:
while (fscanf(FPin, "%99[^\n]", nameBuffer) == 1) {
The 1
ensure you have actually read something into nameBuffer. 1
确保您已实际将某些内容读入nameBuffer。
Also strcpy
does not pad – but you might know that. 而且
strcpy
不会填充-但您可能知道这一点。
将+1移到方括号之外是否有帮助?
walker->name = (char*)malloc(sizeof(char)*(strlen(nameBuffer)+1)); /*ERROR*/
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