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[英]C: Segfault caused by assigning string to struct array using strcpy
[英]C: Using strcpy to transfer one struct element to an array
好的,因此我們應該提示用戶輸入25000行文本。 每行包含三個整數。 然后,我們將該行中的第三個整數傳遞給另一個結構,並連接每個整數,直到您擁有25000個互連的整數。
這是我嘗試過的:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct graph{
int begin;
int end;
int cost;
} PathEdge;
int comp_fcn(const void *a, const void *b) {
return ((PathEdge *) a)->cost - ((PathEdge *) b)->cost;
}
int main(void)
{
int nlines,i;
char r;
int ecost,ebegin,eend;
scanf("%d",&nlines);
PathEdge edges[nlines+1];
for(i=0;i<nlines;i++)
{
scanf("%d, %d, %dn",&ebegin, &eend, &ecost);
edges[i].begin = ebegin;
edges[i].end = eend;
edges[i].cost = ecost;
struct town
{
struct town *north;
int name[25000];
};
struct town *root, *current;
root = malloc(sizeof(struct town));
root->north = NULL;
strcpy (root->name,ecost);
current = malloc(sizeof(struct town));
current->north = root;
strcpy (current->name,ecost);
}
printf("Please enter a node that you want to examine. If you want to exit, please press 'X'.n");
scanf("%c",&r);
switch(r)
{
case 'X':
case 'x':
printf("You entered a wrong value. Gomen. Try againn.");
break;
default:
if((0<r)&&(r<25000))
{
printf("You have accessed node %dn",r);
printf("Its neighboring nodes are %dn",edges[r].cost);
printf("Its neighboring nodes are %dn",edges[i].cost);
}
else
{
printf("Invalid input again. Please do try again. Thanksn");
}
break;
}
return 0;
}
並有警告...“從不兼容的指針類型傳遞strcpy的參數1”“從字符串兼容性傳遞strcpy的參數2使指針從整數轉換而無需強制轉換”預期的char * __限制__,但是當我輸入時參數的類型為'int' 25000行文本,出現分段錯誤。 請幫忙。 謝謝!
您可以使用itoa
將整數轉換為字符串,然后將字符串復制到root-> name。
char str[20];
itoa(ecost, str, 10);
strcpy(root->name, str);
您沒有說明確切的問題,所以我假設您不知所措,在這種情況下,您應該嘗試將實現划分為功能,以便可以處理孤立的問題而不是互連的問題。
這是一個例子:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct graph {
int begin;
int end;
int cost;
} PathEdge;
const char * GenerateInput()
{
static char local[2000];
static int last = 0;
int a, b, c;
a = last++;
b = last++;
c = last++;
sprintf_s(local, 2000, "%i %i %i", a, b, c);
return local;
}
void PathEdgeInitializeFromString(PathEdge * edge, const char * str)
{
sscanf_s(str, "%d %d %dn", &edge->begin, &edge->cost, &edge->end);
}
void QueryAndPrint(PathEdge * edges, int edges_n)
{
printf("Enter a number from 1 to %i: ", edges_n);
int index = 0;
scanf_s("%i", &index);
--index;
if (index < 0 || !(index < (edges_n)))
printf("Error");
else
printf("%i, %i, %i\n", edges[index].begin, edges[index].cost, edges[index].end);
}
int main() {
PathEdge edges[25000];
for (int i = 0; i < 25000; ++i)
{
const char * line = GenerateInput();
PathEdgeInitializeFromString(edges + i, line);
}
QueryAndPrint(edges, 25000);
return 0;
}
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