c - App crashes though I can't understand the reason -

the input file in.wav. have read chunks (succeeded) , read samples normalize audio file...

the problem crashes while trying fing max , min values of .wav file's samples. find minimum value , maximum 1 in array, crashes... tell me wrong, please.

here code:

#include <stdio.h> #include <stdlib.h> #include "main.h" #define hdr_size 64  typedef struct fmt {     char        subchunk1id[4];     int         subchunk1size;     short int   audioformat;     short int   numchannels;     int         samplerate;     int         byterate;     short int   blockalign;     short int   bitspersample;  } fmt;  typedef struct data {     char        subchunk2id[4];     int         subchunk2size;     int         data[441000];  } data;  typedef struct header {     char        chunkid[4];     int         chunksize;     char        format[4];     fmt         s1;     data        s2; } header;    int main() {     file *input = fopen( "in.wav", "rb");   /// namein      if(input == null)     {         printf("unable open wave file (input)\n");         exit(exit_failure);     }      file *output = fopen( "out.wav", "wb"); /// nameout     header hdr;       fread(&hdr, sizeof(char), hdr_size, input);      /* note: chunks has been copied successfully. */       /*###############################*/                                       /*##### update (char *ptr;) #####*/     /*###############################*/     char *ptr;  // 'int' written here instead of 'char'. that's stupid mistake...     long n = hdr.s2.subchunk2size;       /// copying samples...     ptr = malloc(sizeof(hdr.s2.subchunk2size));     while ( n-- != 0 )     {         fread(&ptr, 1, 1, input);  // continues reading after least 'stop' place.      }                              // being told here (on "stack") so...       n = hdr.s2.subchunk2size; // resetting 'n'.     int min = ptr[0], max = ptr[0], i;      /* problem here: */     ( = 0; < n; i++ )         {             if ( ptr[i] < min )     // if next elements less previous, swap them.                 min = ptr[i];             if ( ptr[i] > max ) // if next elements bigger previous, swap them.                 max = ptr[i];     }      printf("> > >%d__%d\n", min, max);    // displaying of 'min' , 'max'.      fclose(input);     fclose(output);      return 0; } 

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update:

eureka! because of 8-bits per sample! must manipulate them ( samples ) type of char. (see "### update ###"-comment in code)

this code:

    /// copying samples...     ptr = malloc(sizeof(hdr.s2.subchunk2size));     while ( n-- != 0 )     {         fread(&ptr, 1, 1, input);  // continues reading after least 'stop' place.      }                              // being told here (on "stack") so... 

overwrites first byte of ptr variable n times. corrupts ptr's value. if fixed read allocated buffer instead (by removing &), rewriting first byte of allocated memory.

what intended was:

    fread(ptr, 1, n, input); 

notice while loop not needed. but, guess on part regarding true intentions.