尝试将stdin读取到2d动态分配的数组时出现分段错误(Segmentation fault when trying to read stdin to a 2d dynamically allocated array)

 我正在尝试从stdin读取动态的字符串数组，使用空格作为分隔符。 代码如下 
 
#include<stdio.h>
#include<stdlib.h>
char** parseInput(size_t *numElements)
{
  char **lines;
  int outerIndex = 0;
  int innerIndex = 0;
  int widths = 1;
  char c=getchar();
  lines =(char**) malloc((outerIndex+1)*sizeof(char*));
  lines[0] = (char*) malloc(sizeof(char));
  while(c!=EOF)
  {
    if(innerIndex==widths)//reallocate each strings length, double it
    {
      widths+=widths;
      int i;
      for(i=0;i<outerIndex+1;i++)
        lines[i]=(char*)realloc(lines[i],(widths+1)*sizeof(char));
    }
    lines[outerIndex][innerIndex]=c;
    innerIndex++;
    if(c==' ')//allocate memory for the next string in the array of strings
    {
      lines[outerIndex][innerIndex]='\0';
      innerIndex=0;
      outerIndex++;
      lines =(char**) realloc(lines,(outerIndex+1)*sizeof(char*));
      lines[outerIndex] = (char*) realloc(lines[outerIndex],(widths+1)*sizeof(char));
      //the above line in the debugger causes a segfault when outerIndex=19
    }
    c=getchar();
  }
  if(innerIndex!=0)//if the last character is not a space, append a space
  {
    if(innerIndex==widths)
    {
      widths+=widths;
      int i;
      for(i=0;i<outerIndex+1;i++)
        lines[i]=(char*)realloc(lines[i],(widths+1)*sizeof(char));
    }
    lines[outerIndex][innerIndex]=' ';
    lines[outerIndex][innerIndex+1]='\0';
  }
  *numElements=(size_t)(outerIndex+1);
  return lines;
}
int main()
{
    size_t num =0;
    char** lines = parseInput(&num);
}
 
 当外部数组大小增加到超过20个变量时，我在指示的行处出现分段错误。 例如，以下输入会导致段错误 
 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
 
 但以下没有 
 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
 
 调试错误说 
 
Program received signal SIGSEGV, Segmentation fault.
0x0000003417e7bf4d in realloc () from /lib64/libc.so.6
 
 这可能是由什么引起的？ 

I'm trying to read from stdin to a dynamic array of strings, using spaces as separators. The code is as follows
 
#include<stdio.h>
#include<stdlib.h>
char** parseInput(size_t *numElements)
{
  char **lines;
  int outerIndex = 0;
  int innerIndex = 0;
  int widths = 1;
  char c=getchar();
  lines =(char**) malloc((outerIndex+1)*sizeof(char*));
  lines[0] = (char*) malloc(sizeof(char));
  while(c!=EOF)
  {
    if(innerIndex==widths)//reallocate each strings length, double it
    {
      widths+=widths;
      int i;
      for(i=0;i<outerIndex+1;i++)
        lines[i]=(char*)realloc(lines[i],(widths+1)*sizeof(char));
    }
    lines[outerIndex][innerIndex]=c;
    innerIndex++;
    if(c==' ')//allocate memory for the next string in the array of strings
    {
      lines[outerIndex][innerIndex]='\0';
      innerIndex=0;
      outerIndex++;
      lines =(char**) realloc(lines,(outerIndex+1)*sizeof(char*));
      lines[outerIndex] = (char*) realloc(lines[outerIndex],(widths+1)*sizeof(char));
      //the above line in the debugger causes a segfault when outerIndex=19
    }
    c=getchar();
  }
  if(innerIndex!=0)//if the last character is not a space, append a space
  {
    if(innerIndex==widths)
    {
      widths+=widths;
      int i;
      for(i=0;i<outerIndex+1;i++)
        lines[i]=(char*)realloc(lines[i],(widths+1)*sizeof(char));
    }
    lines[outerIndex][innerIndex]=' ';
    lines[outerIndex][innerIndex+1]='\0';
  }
  *numElements=(size_t)(outerIndex+1);
  return lines;
}
int main()
{
    size_t num =0;
    char** lines = parseInput(&num);
}
 
When the outer array size grows to anything more than 20 variables, I get a segmentation fault at the indicated line. For example the following input causes a segfault
 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
 
but the following does not
 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
 
The debug error says
 
Program received signal SIGSEGV, Segmentation fault.
0x0000003417e7bf4d in realloc () from /lib64/libc.so.6
 
What could this be caused by?

原文：https://stackoverflow.com/questions/41990269