c - Segmentation fault after exit function -

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• crash or “segmentation fault” when data copied/scanned uninitialized pointer 2 answers

parse line function handler:

char **parse_line(char *input) {     char **tokens;     char *token;     char *seps = " \n";      token = strtok(input, seps);     int = 0;     while (token != null) {         tokens[i] = token;         i++;          token = strtok(null, seps);     }      tokens[i] = null;      return tokens; } 

pipe function handler:

void pipes(char *input) {     const char ch = '|';     printf("%s", input);      char *c;      if (strchr(input, ch) == null) {         printf("no | found\n");         return;     }      printf("%s\n", input);      char *p = strtok(input, "|");      int = 0;     char *array0;     char *array1;      while (p != null) {         if (i == 0)             array0 = p;         else             array1 = p;         i++;         printf("p: %s\n", p);          p = strtok( null, "|" );     }      printf("opening\n");      parse_line(array1); } 

main

int main(int argc, const char *argv[]) {     while (1) {         printf("> ");         //read line         char input[100];         fgets(input, sizeof(input), stdin);          pipes(input);     }     ... 

gdb output:

(gdb) cat scores | grep villanova undefined catch command: "scores | grep villanova".  try "help catch". (gdb) run starting program: *******  > cat scores | grep villanova cat scores | grep villanova cat scores | grep villanova  while while opening  grep villanova   program received signal sigsegv, segmentation fault. 0x00007fffffffddf2 in ?? () (gdb) x/s 0x00007fffffffddf2 0x7fffffffddf2: "villanova" (gdb) p $_siginfo._sifields._sigfault.si_addr $1 = (void *) 0x7fffffffddf2 (gdb) q 

when stepping through gdb seg faults after reaches end of pipes function. have idea why/ how can find out why , fix it.

i'm trying better @ debugging has stumped me , i'd appreciate can :)

the function parse_line not allocate array tokens point to. code has undefined behavior.

here simple corrected version:

char **parse_line(char *input) {     size_t = 0;     char **tokens = malloc(sizeof(*tokens));     char *token;     const char *seps = " \n";     if (tokens == null)         return null;      token = strtok(input, seps);     while (token != null) {         char **newp = realloc(tokens, (i + 2) * sizeof(*newp));         if (newp == null) {             free(tokens);             return null;         }         tokens = newp;         tokens[i++] = token;         token = strtok(null, seps);     }     tokens[i] = null;      return tokens; }