我必须写一个快速排序，它会得到一个txt，它具有最常用的密码及其频率。
我还有一个必须正确的文件 main.c 。我只需要编写快速排序的函数。
当我查看代码时，似乎一切都很好。我还使用了valgrind，但我无法找到错误。
看一下，代码末尾是valgrind的结果。
#define _POSIX_C_SOURCE 200809L
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "quicksort.h"
void init_list(list *mylist) {
mylist = (list*)malloc(sizeof(list));
mylist->first = NULL;
mylist->last = NULL;
}
void insert_list(list_element *le, list *mylist) {
le->next = NULL;
if (mylist->first == NULL) {
mylist->first = le;
mylist->first->next = NULL;
if (mylist->last == NULL) {
mylist->last = le;
}
} else
if (mylist->first != NULL) {
if (mylist->first->next == NULL) {
mylist->first->next = le;
mylist->last = le;
} else
if (mylist->first->next != NULL) {
list_element *h = mylist->first->next;
list_element *hc = NULL;
while (h != NULL) {
hc = h;
h = h->next;
}
hc->next = le;
mylist->last = le;
}
}
}
void free_list(list *mylist) {
list_element *zaehler;
list_element *zaehler2 = NULL;
for (zaehler = mylist->first; zaehler != mylist->last; zaehler = zaehler2) {
zaehler2 = zaehler->next;
free(zaehler);
}
free(mylist);
}
void read_data(char *filename, list *mylist) {
FILE *input = fopen(filename, "r");
if (input == NULL) {
printf("Could not open file\n");
return;
}
char *zeile = malloc(50 * sizeof(char));
char *leer = " ";
while (fgets(zeile, 50, input) != NULL) {
char *token1 = strtok(zeile, leer);
char *token2 = strtok(NULL, "\n");
list_element *new;
new = (list_element*)malloc(sizeof(list_element));
new->password = token1;
new->count = atoi(token2);
insert_list(new, mylist);
}
}
list_element *partition(list *input, list *left, list *right) {
list_element *pivot = input->first;
list_element *zaehler = pivot->next;
while (zaehler != input->last) {
if (zaehler->count < pivot->count) {
insert_list(zaehler, left);
} else {
insert_list(zaehler, right);
}
}
if (zaehler == input->last) {
if (zaehler->count < pivot->count) {
insert_list(zaehler, left);
} else {
insert_list(zaehler, right);
}
}
return pivot;
}
void qsort_list(list *mylist) {
if (mylist->first == mylist->last) {
return;
} else {
list *left = NULL;
list *right = NULL;
list_element *pivot;
pivot = partition(mylist, left, right);
qsort_list(left);
qsort_list(right);
if (left->first == NULL) {
mylist->first = pivot;
} else {
mylist->first = left->first;
left->last->next = pivot;
}
if (right->first == NULL) {
pivot->next = NULL;
mylist->last = pivot;
} else {
pivot->next = right->first;
mylist->last = right->last;
}
}
}
void print_list(list *mylist) {
list_element *first = mylist->first;
list_element *last = mylist->last;
list_element *zaehler;
for (zaehler = first; zaehler != last; zaehler = zaehler->next) {
printf("%s %d\n", zaehler->password, zaehler->count);
}
printf("%s %d\n", last->password, last->count);
}
这是VALGRIND所说的：
==4996== Memcheck, a memory error detector
==4996== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==4996== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==4996== Command: ./a1 Eingabedaten_quicksort_unsortiert
==4996==
==4996== Conditional jump or move depends on uninitialised value(s)
==4996== at 0x4007DC: insert_list (introprog_quicksort.c:34)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996==
==4996== Conditional jump or move depends on uninitialised value(s)
==4996== at 0x400824: insert_list (introprog_quicksort.c:42)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996==
==4996== Use of uninitialised value of size 8
==4996== at 0x400831: insert_list (introprog_quicksort.c:43)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996==
==4996== Use of uninitialised value of size 8
==4996== at 0x40085E: insert_list (introprog_quicksort.c:47)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996==
==4996== Use of uninitialised value of size 8
==4996== at 0x40086E: insert_list (introprog_quicksort.c:48)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996==
==4996== Invalid read of size 8
==4996== at 0x40088C: insert_list (introprog_quicksort.c:52)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996== Address 0x111e2d8d48550030 is not stack'd, malloc'd or (recently) free'd
==4996==
==4996==
==4996== Process terminating with default action of signal 11 (SIGSEGV)
==4996== General Protection Fault
==4996== at 0x40088C: insert_list (introprog_quicksort.c:52)
==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
==4996== by 0x400C8C: main (main_quicksort.c:13)
==4996==
==4996== HEAP SUMMARY:
==4996== in use at exit: 642 bytes in 4 blocks
==4996== total heap usage: 5 allocs, 1 frees, 4,738 bytes allocated
==4996==
==4996== 16 bytes in 1 blocks are definitely lost in loss record 1 of 4
==4996== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==4996== by 0x40079B: init_list (introprog_quicksort.c:24)
==4996== by 0x400C72: main (main_quicksort.c:12)
==4996==
==4996== LEAK SUMMARY:
==4996== definitely lost: 16 bytes in 1 blocks
==4996== indirectly lost: 0 bytes in 0 blocks
==4996== possibly lost: 0 bytes in 0 blocks
==4996== still reachable: 626 bytes in 3 blocks
==4996== suppressed: 0 bytes in 0 blocks
==4996== Reachable blocks (those to which a pointer was found) are not shown.
==4996== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==4996==
==4996== For counts of detected and suppressed errors, rerun with: -v
==4996== Use --track-origins=yes to see where uninitialised values come from
==4996== ERROR SUMMARY: 7 errors from 7 contexts (suppressed: 0 from 0)
Segmentation fault
答案 0 :(得分：1)
将来，对您不了解的错误消息提出问题可能会有所帮助。尝试像＃34;什么意思？＆＃34;或者＆＃34;我如何破译......？＆＃34;。
==4996== Conditional jump or move depends on uninitialised value(s) ==4996== at 0x4007DC: insert_list (introprog_quicksort.c:34)
这告诉你在第34行使用了未初始化的值。让我们来看看第34行：
if ( mylist->first == NULL ) { //c.34
因此mylist或mylist->first未初始化。让我们深入研究您粘贴的痕迹，如下一行所示，到第90行：==4996== by 0x4009D1: read_data (introprog_quicksort.c:90)
new = (list_element*)malloc(sizeof(list_element));
new->password = token1;
new->count = atoi(token2);
insert_list(new, mylist); //c.90
啊！我知道了！ mylist->first未初始化，因为尚未分配给它！巧合多少？我想不是。这很有道理。
既然您已经了解了这些错误消息，那么您应该能够完成剩下的工作并清除它们......您的段错误可能是由这些错误造成的。
另见BLUEPIXY留下的评论;他们需要考虑的有用点。