[英]Why does the second malloc fail in this scenario?
我目前正在處理一段代碼,我們正在解析文件並使用不同的函數。 通過使用printf
調用進行調試,我發現在第二次malloc
調用中出現 memory 錯誤。 什么可能導致第二個malloc
在這個粗略的骨架中失敗?
struct example {
char *myChar;
int myInt;
};
struct example *doThing(FILE *file) {
struct example *myToken = (struct example *)malloc(sizeof(struct example));
char buffer[32] = "";
// other stuff
if (strncmp(buffer, "random", 6) == 0) {
strncpy(myToken->myChar, buffer, 6);
myToken->tokenid = 1;
return myToken;
}
return NULL;
}
struct example *doThing2(FILE *file) {
struct example *myOtherToken = (struct example *)malloc(sizeof(struct example));
// other stuff
return myOtherToken;
}
int main() {
FILE *ofp = fopen("thefile.txt", "r");
struct example *token1, *token2;
token1 = doThing(ofp);
token2 = doThing2(ofp);
// other stuff
free(token1);
free(token2);
return 0;
}
您正面臨 memory 泄漏。 按照以下兩個示例之一更正您的代碼
是的,正如@Eugene_Sh 提到的,您應該為myToken->myChar
分配 memory 並且不要忘記在釋放 myToken 之前釋放它
struct example* doThing(FILE *file) { char buffer[32] = ""; // other stuff if (strncmp(buffer, "random", 6) == 0) { struct example *myToken = (struct example *) malloc(sizeof(struct example)); myToken ->myChar= malloc(7); strncpy(myToken ->myChar, buffer, 6); myToken ->myChar[6]=0; myToken->tokenid = 1; return myToken; } return NULL; }
樣品 2
struct example* doThing(FILE *file) { struct example *myToken = (struct example *) malloc(sizeof(struct example)); char buffer[32] = ""; // other stuff if (strncmp(buffer, "random", 6) == 0) { myToken ->myChar= malloc(7); strncpy(myToken ->myChar, buffer, 6); myToken ->myChar[6]=0; myToken->tokenid = 1; return myToken; } free(myToken ); return NULL; }
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