c - Garbage being printed when using strcpy

Question

I have a function that will parse some data coming in. My problem is that after using strncpy I get some garbage when I try to print it. I try using malloc to make the char array the exact size.

Code:

void parse_data(char *unparsed_data)
{
char *temp_str;
char *pos;
char *pos2;
char *key;
char *data;
const char newline = '
';

int timestamp = 0;

temp_str = (char*)malloc(strlen(unparsed_data));

g_print("
The original string is: 
%s
",unparsed_data);


//Ignore the first two lines
pos = strchr(unparsed_data, newline);
strcpy(temp_str, pos+1);
pos = strchr(temp_str, newline);
strcpy(temp_str, pos+1);

//Split the line in two; The key name and the value
pos = strchr(temp_str, ':'); // ':' divides the name from the value
pos2 = strchr(temp_str, '
'); //end of the line
key = (char*)malloc((size_t)(pos-temp_str)-1); //allocate enough memory
data = (char*)malloc((size_t)(pos2-pos)-1);

strncpy(key, temp_str, (size_t)(pos-temp_str));
strncpy(data, pos + 2, (size_t)(pos2-pos));

timestamp = atoi(data);

g_print("size of the variable "key" = %d or %d
", (size_t)(pos-temp_str), strlen(key));
g_print("size of the variable "data" = %d or %d
", (size_t)(pos2-pos), strlen(data));

g_print("The key name is %s
",key);
g_print("The value is %s
",data);
g_print("End of Parser
");
  }

Output:

The original string is: 
NEW_DATAa_PACKET
Local Data Set 16-byte Universal Key
Time Stamp (microsec): 1319639501097446
Frame Number: 0
Version: 3
Angle (deg): 10.228428

size of the variable "key" = 21 or 22
size of the variable "data" = 18 or 21
The key name is Time Stamp (microsec)
The value is 1319639501097446
F32
End of Parser

Run it again:

  The original string is: 
  NEW_DATAa_PACKET
  Local Data Set 16-byte Universal Key
  Time Stamp (microsec): 1319639501097446
  Frame Number: 0
  Version: 3
  Angle (deg): 10.228428

  size of the variable "key" = 21 or 25
  size of the variable "data" = 18 or 18
  The key name is Time Stamp (microsec)ipe 
  The value is 1319639501097446
  F
  End of Parser

Answer 1

Your results are because strncpy does not put a null character at the end of the string.