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PODynamic memory allocation in a multiple-files project in C
 

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  1. PODynamic memory allocation in a multiple-files project in C
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    <p>I am asked to implement an analogue to the <code>string.h</code> library. However, I am not allowed to use the <code>'\0'</code> inside my library to end my string; that's why I am supposed to use a structure for strings in my program. I have this in <code>mystring.h</code> file:</p> <pre><code>#include &lt;stdio.h&gt; #define MAXSTRLEN 100 // Defining the maximum lenght of the string as being 100 typedef struct scell *mystring_t; mystring_t makemystring (char cs[]); // This function stores a given string into the mystring structure </code></pre> <p>I have this in <code>mystring.c</code>file:</p> <pre><code>#include &lt;stdlib.h&gt; #include "mystring.h" // including the header file of mystring library struct scell { char *string; int length; }; mystring_t makemystring (char cs[]){ //Storing a string into the structure int i = 0; mystring_t ns; ns-&gt;string=(char*)calloc(MAXSTRLEN ,sizeof(char)); // printf ("I allocated memory for the string"); while (cs[i] != '\0') { printf ("\nI entered into the while\n"); ns-&gt;string[i] = cs[i]; printf ("I inserted\n"); i++; printf ("I incremented the count\n"); } ns-&gt;length=i; // storing the length of the string into the structure printf ("%d\n", ns-&gt;length); printf ("refreshed the length\n"); printf ("%d", ns-&gt;length); return ns; } </code></pre> <p>I have this in the <code>main.c</code> file:</p> <pre><code>#include "mystring.h" #include &lt;stdlib.h&gt; int main () { int result; mystring_t S1; mystring_t S2; // create two strings S2 = makemystring("Bye"); printf("I got out of the makemystring function\n"); S1 = makemystring("Hi"); </code></pre> <p>These <code>printf()</code> calls are just debugging statements. It seems to me that the function makemystring works correctly but I have a crash at the level of returning. Can anyone please help?</p>
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    1. USJonathan Leffler
    1. USuser1680944
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    1. COOne big problem: ns is a wild pointer - you never allocate any memory for the struct.
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      1. PODynamic memory allocation in a multiple-files project in C
      1. USPaul R
    2. COProbably you could correct your program by removing the star in the `typedef` of `mystring_t`. Another problem: If the string you pass to makemystring is longer than MAXSTRLEN you will get a buffer overflow. You should be more careful there.
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      1. PODynamic memory allocation in a multiple-files project in C
      1. USJohnB
 

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