c - 为什么会出现段错误？斯特托克？

Question

所以我很好奇为什么下面的代码段总是出现段错误。对我来说这看起来是正确的。

int * addCoins(char *val){
    const char *deli = ",";
    char *ptr =NULL;

    char *denomination = strtok_r(val, deli, &ptr);
    char *count = strtok_r(NULL, deli, &ptr);
    int deno = atoi(denomination);
    int cnt = atoi(count);
    int *k;
    k = malloc(sizeof(*k)*2);
    k[0] = deno;
    k[1] =cnt;

    return k;
}

调用main中的addCoins函数。我不认为问题出在这里，但老实说我对这个问题有点茫然。

char* fileNameCoin = argv[2];
FILE *fileCoin;
fileCoin = fopen(fileNameCoin, "r+");
char bufCoin[256];
int i = 0;
//vmNode->next = NULL;
int *j;
while (fgets(bufCoin, sizeof bufCoin, fileCoin) != NULL) {
    j = addCoins(bufCoin);
    int deno = j[0];
    switch(deno){
        case 5:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 10:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 20:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 50:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 100:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 200:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 500:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        case 1000:
            Coins[i].denom = j[0];
            Coins[i].count = j[1];
            break;
        default:
            break;
    }

    i++;
}

以下是文件的定义方式

1000,3
500,4
200,20
100,30
50,5
20,3
10,40
5,20

其中第一个数字是以分为单位的面额，第二列是所述面额的数字。

这些是类型定义:

/* The different denominations of coins available */
enum denomination
{
    FIVE_CENTS, TEN_CENTS, TWENTY_CENTS, FIFTY_CENTS, ONE_DOLLAR,
    TWO_DOLLARS, FIVE_DOLLARS, TEN_DOLLARS
};

/* Each coin in the coins array will have a denomination (20 cents,
 * 50 cents, etc) and a count - how many of that coin do we have on hand
 */
struct coin
{
    enum denomination denom;
    unsigned count;
};

Answer 1

老实说，您应该通过typedef更好地使用struct。示例(使用 exename in.txt 调用):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* The different denominations of coins available */
enum denomination {
    FIVE_CENTS, TEN_CENTS, TWENTY_CENTS, FIFTY_CENTS, ONE_DOLLAR,
    TWO_DOLLARS, FIVE_DOLLARS, TEN_DOLLARS
};

typedef struct {
    enum denomination denom;
    unsigned int count;
} coin;

coin * addCoins(char *val) {
    coin *k = malloc(sizeof(coin));
    if( sscanf( val, "%d,%d", &(k->denom), &(k->count)) != 2 ) {
      fprintf(stderr,"Two int values not found on line '%s' in input.\n", val);
      free(k);
      k=NULL;
    }
    return k;
} 

int main(int argc, char *argv[])
{
    coin Coins[100]={0};
    char* fileNameCoin = argv[1];
    FILE *fileCoin = fopen(fileNameCoin, "r+");
    char bufCoin[256];
    int i = 0;
    coin *j;
    if( fileCoin ) {
      while(fgets(bufCoin, sizeof bufCoin, fileCoin) != NULL) {
        j = addCoins(bufCoin);                                                                                       
        if( j ) { // only add if 2 int values found on input line
          Coins[i] = *j;
          free(j);
          printf("c: %d, %d\n", Coins[i].denom, Coins[i].count);
          i++;
        } 
      }
      fclose(fileCoin);
    }
    else {
      fprintf(stderr,"Unable to open file %s for input.\n",fileNameCoin);
    }
}