Here is my code in C, I was declaring L as a non-pointer variable but then after running the program I realized that it didn't really change the values in the array after calling the Insert function. So I changed the declaration of L as
SeqList* L
where I put an extra * sign and correspondingly changed those . to -> , but now I keep getting the
Segmentation fault (core dumped)
message? Where did I miss something? Thanks!
#include "stdio.h"
#define MAXSIZE 100
typedef struct SeqList{
int elem[MAXSIZE];
int last;
} SeqList;
int GetData(SeqList* L,int i){
return L->elem[i];
}
void Insert(SeqList* L, int i, int e){
int temp;
if (i < 1 || i > L->last + 2){
printf("Invalid Inserting point.\n");
}
if (L->last > MAXSIZE){
printf("List already full.\n");
}
for(temp = L->last; temp != i; temp--){
L->elem[temp+1] = L->elem[temp];
}
L->elem[temp] = e;
L->last++;
}
int main(){
SeqList* L;
int i;
for(i=0;i<10;i++){
L->elem[i] = i*i;
}
Insert(L,5,10);
for(i=0;i<10;i++){
printf("%d\n", L->elem[i]);
}
printf("%d\n", GetData(L,5));
}
The following block of code is not good because you have not allocated memory for L
and are using it as if it points to valid memory.
SeqList* L;
int i;
for(i=0;i<10;i++){
L->elem[i] = i*i;
}
That explains the segmentation fault.
I'm not sure what you had tried before trying the above but the following program works for me.
#include "stdio.h"
#define MAXSIZE 100
typedef struct SeqList{
int elem[MAXSIZE];
int last;
} SeqList;
int GetData(SeqList* L,int i){
return L->elem[i];
}
void Insert(SeqList* L, int i, int e){
int temp;
if (i < 1 || i > L->last + 2){
printf("Invalid Inserting point.\n");
}
if (L->last > MAXSIZE){
printf("List already full.\n");
}
for(temp = L->last; temp != i; temp--){
L->elem[temp+1] = L->elem[temp];
}
L->elem[temp] = e;
L->last++;
}
int main(){
SeqList L;
int i;
for(i=0;i<10;i++){
L.elem[i] = i*i;
}
L.last = 10;
Insert(&L,5,10);
for(i=0;i<10;i++){
printf("%d\n", L.elem[i]);
}
printf("%d\n", GetData(&L,5));
}
You haven't pointed L to an allocated memory. You could try this:
SeqList* L = malloc(sizeof(SeqList));
Caveats :
SeqList* L;
L
could be a garbage value and may point to any address causing serious memory exceptoins. Never access pointer without allocation or without pointing it to an already allocated/initialized memory, ie
SeqList* L = malloc(sizeof(SeqList)); //OR SeqList initalizedList = {0}; SeqList* L = &initalizedList;
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