我正在做一个练习,似乎printf()正在某个地方写我的变量。我正在处理一个结构,它包含一个指向指向结构的指针数组的指针,因此我确信我在某个地方分配了一些稍微有点错误的内容。
int dictionary_add(struct dictionary* d,
const char * const english,
const char * const foreign){
/* ROLE Adds a new wordPair made of strdup copies of the parameter strings
to a dictionary d
RETURNS 0 if everything went fine
PARAMETERS d the dictionary to work with
english string representing the english part of the new wordPair
foreign string representing the foreign part of the new wordPair
*/
//Determine where in the array the wordPair is going.
int location;
location=((d->size)-(d->nbwords))-1;
printf("Adding data to array location: %i\n\n",location);
//Build the wordPair
const struct wordPair newPair={english,foreign};
//Add the wordPair
d->data[0]=&newPair;
//***************This is where the problem shows up***************
printf("Added english:%s\n",d->data[0]->englishWord);
//d->data[0]=&newPair; //When uncommeted, program doesn't crash.
printf("Added english:%s\n",d->data[0]->englishWord);
d->nbwords++;
return 0;
}
如何从main()调用:
const char* english=malloc(sizeof(char)*6);
const char* foreign=malloc(sizeof(char)*6);
strcpy(english,"hello");
strcpy(foreign,"holla");
词典的创建位置:
struct dictionary *dictionary_build(int size){
/* ROLE Allocate and initialize a new dictionary structure able to accomodate a number of
pairs of words specified by the size parameter
RETURNS Address of new dictionary, if allocation was successfull.
NULL otherwize
PARAMETERS The size of the dictionary to make
*/
struct dictionary *d=malloc(sizeof(struct dictionary));
d->size=size;
d->nbwords=0;
struct wordpair* wordPairs[size]; //create array of pointers to wordpairs
d->data=&wordPairs; //Set pointer to array of pointers to wordpairs
return d;
}
结构:
struct wordPair {
char* englishWord;
char* foreignWord;
};
struct dictionary {
struct wordPair ** data;
int nbwords;
int size;
};
提前谢谢你的帮助。我并不反对我的整个设计忽略了这一点。我可以更改结构定义和预期参数之外的任何内容。
最佳答案
当您这样做时:
struct wordpair* wordPairs[size];
d->data=&wordPairs;
return d;
}
wordPairs
具有自动存储,其生存期将在函数返回时结束。试图在对象生命周期结束后引用它是未定义的行为,但是您在d
中保留了指向它的指针,然后在dictionary_add()
中尝试取消引用。改用
d->data = malloc(size * sizeof(struct wordpair *));
或类似的词。不要忘记检查malloc()
的返回以确定它是否成功,并且(通常)在完成后检查free()
所有内容。关于c - C- printf()正在覆盖我的变量,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/23051720/