此代码尝试对结构数组应用合并排序并对其进行排序。合并排序函数中存在段错误,我无法预测原因。我也附上了输出,如果需要任何东西,请告诉我。
#include<stdio.h>
#include<stdlib.h>
typedef struct node node;
struct node{
int index; // record-key
char fname[20], lname[20], dob[20], location[20], dept[20];
}demo,delta;
node delta ={-1,'a','a','a','a','a'};
void merge(node [], int, int, int );
void mergesort(node [], int , int );
void mergesort(node a[], int start, int end){
int mid = (start+end)/2;
if(start<end){
mergesort(a,start,mid);
mergesort(a,mid+1,end);
merge(a,start,mid,end);
}
}
void merge(node a[], int start, int mid, int end){
node *b = malloc(sizeof(demo)*end*2); //creating two arrays
node *c = malloc(sizeof(demo)*end*2);
int j=0,k=0,i=0,e=0,f=0;
for(i=start;i<mid+1;i++){ //storing first half of main array into b
b[i] = a[i];
}
b[i+1]=delta; //this is a check value used for checking the length in a loop below
for(k=mid+1;k<end+1;k++){ //storing second part of main array into c
c[j]=a[k];
j++;
}
c[j+1]=delta; //this is just a check value to check length
for(i=start;i<end+1;i++){
if(b[e].index==delta.index){ //if array b ends
while(c[f].index!=delta.index){
a[i]=c[f]; //copy remaining contents of c into a
i++;
f++;
}
break;
}
if(c[f].index==delta.index){ //if c ends
while(b[e].index!=delta.index){ //copy remaining contents of b into a
a[i]=b[e];
i++;
e++;
}
break;
}
if(b[e].index>c[f].index){ //compring first element of both b and c and overriding smaller value in main array
a[i]=c[f];
f++;
}
else if(b[e].index<=c[f].index){ //compring first element of both b and c and overriding smaller value in main array
a[i]=b[e];
e++;
}
}
for(i=0;i<end+1;i++){
printf("arr index: %d \n",a[i].index); //just for checking
}
}
int main(int argc ,char *argv[]){
printf("entered in main\n");
char temp[20];
int i;
FILE *fp =fopen(argv[1],"r");
// printf("bakri\n");
if(fp==NULL){
printf("file not opened\n");
exit(1);
}
node demo;
printf("demo made %ld\n",sizeof(demo));
int var = atoi(argv[2]);
node *arr = malloc(sizeof(demo)*var*2);
if(arr==NULL){
printf("arr is null\n");
exit(2);
}
printf("array made\n");
for(i=0;i<(atoi(argv[2]));i++){
fgetc(fp);
fscanf(fp,"%s %s %s %s %s %s",temp,arr[i].fname,arr[i].lname,arr[i].dob,arr[i].location,arr[i].dept);
arr[i].index=atoi(temp);
}
fclose(fp);
for(i=0;i<atoi(argv[2]);i++){
printf("\n%d",arr[i].index);
}
int len = atoi(argv[2]);
mergesort(arr,0,len-1);
for(i=0;i<len;i++){
printf("%d \n",arr[i].index);
}
return 0;
}
输出是-
entered in main
demo made 104
array made
28053
31163
3786
33086
16355
4792
26524
21076
21367
27286arr index: 28053
arr index: -414853824
Segmentation fault (core dumped)
最佳答案
你分配的数组的最大索引:
node *c = malloc(sizeof(demo)*end);
是end - 1
。然后你有:
for(k=mid+1;k<end+1;k++){
c[j]=a[k];
j++;
}
您将超出数组的边界,这将导致段错误。
关于c - 使用 malloc 的段错误,用于合并排序的结构数组,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43348155/