kb.iu.edu Identify what's causing segmentation faults (segfaults)
NOTE:
1、通过这篇文章可知，和memory相关的错误，都输segment fault
Overview
A segmentation fault (aka segfault) is a common condition that causes programs to crash; they are often associated with a file named core. Segfaults are caused by a program trying to read or write an illegal memory location.
Program memory is divided into different segments: a text segment for program instructions, a data segment for variables and arrays defined at compile time, a stack segment for temporary (or automatic) variables defined in subroutines and functions, and a heap segment for variables allocated during runtime by functions, such as malloc (in C) and allocate (in Fortran). For more, see About program segments.
A segfault occurs when a reference to a variable falls outside the segment where that variable resides, or when a write is attempted to a location that is in a read-only segment. In practice, segfaults are almost always due to trying to read or write a non-existent array element, not properly defining a pointer before using it, or (in C programs) accidentally using a variable's value as an address (see the scanf example below).
Examples of common segfaults
access null pointer
For example, calling memset() as shown below would cause a program to segfault:
memset((char *)0x0, 1, 100);
array out of bound
/* "Array out of bounds" error valid indices for array foo are 0, 1, ... 999 */ int foo[1000]; for (int i = 0; i <= 1000 ; i++) foo[i] = i;
/* Illegal memory access if value of n is not in the range 0, 1, ... 999 */ int n; int foo[1000]; for (int i = 0; i < n ; i++) foo[i] = i;
/* Illegal memory access because no memory is allocated for foo2 */ float *foo, *foo2; foo = (float*)malloc(1000); foo2[0] = 1.0;
integer as address
Another common programming error that leads to segfaults is oversight in the use of pointers. For example, the C function scanf() expects the address of a variable as its second parameter; therefore, the following will likely cause the program to crash with a segfault:
int foo = 0; scanf("%d", foo); /* Note missing & sign ; correct usage would have been &foo */
write a read-only location
A segfault will occur when a program attempts to operate on a memory location in a way that is not allowed (for example, attempts to write a read-only location would result in a segfault).
stack overflow
Segfaults can also occur when your program runs out of stack space. This may not be a bug in your program, but may be due instead to your shell setting the stack size limit too small.