我使用以下代码在堆上加载一个大型哈希表。然而，我不知道加载后搜索整个数组的正确语法。
我想我可以在最后一个J循环中添加一个strcmp？？
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int lines_allocated = 128;
int max_line_len = 100;
/* Allocate lines of text */
char **words = (char **)malloc(sizeof(char*)*lines_allocated);
if (words==NULL)
{
fprintf(stderr,"Out of memory (1).n");
exit(1);
}
FILE *fp = fopen("hashtable.txt", "r");
if (fp == NULL)
{
fprintf(stderr,"Error opening file.n");
exit(2);
}
int i;
for (i = 0; 1; i++)
{
int j;
/* Have we gone over our line allocation? */
if (i >= lines_allocated)
{
int new_size;
/* Double our allocation and re-allocate */
new_size = lines_allocated*2;
words = (char **)realloc(words,sizeof(char*)*new_size);
if (words == NULL)
{
fprintf(stderr,"Out of memory.n");
exit(3);
}
lines_allocated = new_size;
}
/* Allocate space for the next line */
words[i] = malloc(max_line_len);
if (words[i] == NULL)
{
fprintf(stderr,"Out of memory (3).n");
exit(4);
}
if (fgets(words[i], max_line_len-1,fp) == NULL)
break;
/* Get rid of CR or LF at end of line */
for (j = strlen(words[i]) - 1; j >= 0 && (words[i][j] == 'n' || words[i][j] == 'r')j--);
words[i][j] = ' ';
}
int j;
for(j = 0; j < i; j++)
printf("%sn", words[j]);
// Search for a string e.g "ffffffffff999999999922222222227777777777" in words[]
//
//strcmp ( string, words[j])????
//
//
//
/* Good practice to free memory */
for (;i>=0;i--)
free(words[i]);
free(words);
return 0;
}
我曾尝试在循环中实现strcmp，但后来程序出现了segfault。使用此示例：
/* what is i? the number of items used in the array? */
for(x = 0; x < i; x++) {
if ( strcmp( new_name, names[x] ) == 0 ){
/* match, x is the index */
return x;
}
}
/* here with no match */
return -1;
当我缩进你的代码时，我看到了：
for (j = strlen(words[i]) - 1; j >= 0 && (words[i][j] == 'n' || words[i][j] == 'r')j--);
我想你的意思是：
for (j = strlen(words[i]) - 1; j >= 0 && (words[i][j] == 'n' || words[i][j] == 'r'); j--)
----^^^^^^^
那个while永远不会执行它在大括号之间的内容。
您在这里遇到问题：
for (j=strlen(words[i]) - 1; j>=0 && (words[i][j]=='n' || words[i][j]=='r'); j--);
words[i][j]=' ';
j关闭1。你应该在循环后增加j：
for (j=strlen(words[i])-1; j>=0 && (words[i][j]=='n' || words[i][j]=='r'); j--)
{
}
words[i][j + 1] = ' ';
额外的{ }仅用于可读性目的。否则，如果在for之后忘记了;，则代码将正确编译，但words[i][j +1 ]=' ';是循环的一部分。
其他关闭一个问题：
您必须在此递减i：
/* Good practice to free memory */
i-- ; // <<<< decrement i here
for (;i>=0;i--)
free(words[i]);
strcmp问题：
关于你的strcmp问题，你可能想要这个：
int j;
for(j = 0; j < i; j++)
{
printf("%sn", words[j]);
if (strcmp (words[j], "word we are lookong for") == 0)
{
// found it
}
}