我的程序收到信号SIGSEGV，分段错误，请帮忙

Question

When I try to run this program, it doesn't work. When I go to debugs, a message pops up "program received signal sigsegv, segmentation fault"

i debug the programe with gdb, and this is the messages. Program received signal SIGSEGV, Segmentation fault. 0x0000555555555195 in ft_atoi (str=0x555555556004 "111") at ft_atoi.c:33 33 while (ft_isspace(str[i]))

#include <string.h>
#include <stdio.h>

static int ft_isspace(char c)
{
  if (c == '\n' || c == '\f' || c == ' ' ||
      c == '\r' || c == '\v' || c == '\t');
  return (1);
  return (0);
}
 
int ft_atoi(const char *str)
{
  int               i;
  int               n;
  int               signe;

  n = 0;
  i = 0;
  signe = 1;
  while (ft_isspace(str[i]))
    i++;
  if (str[i] == '-' || str[i] == '+')
    {
      if (str[i++] == '-')
    signe = -1;
    }
  while (str[i] >= '0' && (str[i] <= '9') && str[i] != '\0')
    {
      if (((unsigned long)n > 9223372036854775807 / 10) ||
      (((unsigned long)n == 9223372036854775807 / 10) &&
       ((unsigned long)n % 10) > 7))
    return ((signe > 0 ? -1 : 0));
      n = n * 10 + (*(str + (i++)) - '0');
    }
  return (n * signe);
}
int main()
{
  printf("%d", ft_atoi("111"));
  return 0;
}

Answer 1

static int ft_isspace(char c)
{
  if (c == '\n' || c == '\f' || c == ' ' ||
      c == '\r' || c == '\v' || c == '\t');
  return (1);
  return (0);
}

This will always return 1, causing the loop to run off the end. Notice the semicolon here:

      c == '\r' || c == '\v' || c == '\t'); <-- HERE

Imagine if it looked like this:

      c == '\r' || c == '\v' || c == '\t') j=2;

That would cause the if statement to decide whether j=2 is executed. And the return on the next line would execute regardless of the results of the if .

Well your code does that same thing, except instead of j=2 , you have an empty statement.

The syntax is: if <expression> <statement>

Your expression ends with that last close parenthesis. So your controlled statement is just the ; .

Just remove that semicolon so the return is the statement that is controlled by the if and that appears immediately after the expression.