Insert string to double array [closed] - c

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I got help here a few days ago in the construction of a function that gets a string of the like:
"1 2.2 3 4.4 5 6.6 7 8.5"
and insert it to array[2][4] (in this case) in the following form:
1 | 3 | 5 | 7
2.2|4.4|6.6|8.5
the function that do that the array is:
//'function' is char*,'array' is double array
for(p = function; *p != '\0' ;p++){//convert double by strtod
item = strtod(p, &p);
++div;
if((div%2)!=0)
{
array[0][j]=item;
}
else
{
array[1][j++]=item;
div=0;
}
}
the problem in the code that the function insert the values only to array[0][j] and not to array[1][j] the meaning the array seems like(if the array initialized to 0 in the begin):
1 | 3 | 5 | 7
0 | 0 | 0 | 0
the values insert only to the first line of the array,
if i call to the function with string:
"0.5 2 1 4 3 6 0.5 8"
so item always be 0 and i don't know why :\
The previous post:
Try to insert string to array to check if the string describe function
thanks

Answer 1

Initially, your code works. But then your pointer, p, is being incremented past the end of the string and you are seeing whatever is in memory after that, and overwriting the contents of your array. The problem is here:
for(p = function; *p != '\0' ;p++) {
item = strtod(p, &p);
// (other code)
}
After calling strtod for the very last number (8.5), the pointer p already points to the NULL terminator. But then, your for loop calls p++ which increments it one past the NULL terminator. Your function continues running for some time after that, filling the array with garbage and possibly corrupting memory.
A solution is:
for(p = function; *p != '\0' ;) {
item = strtod(p, &p);
// (other code)
}
In this case, on most iterations, p points to the space before each number. That is okay, since strtod explicitly ignores whitespace. After the last iteration, p points to the NULL terminator and your loop ends before corrupting the array and possibly other parts of memory.
Dealing with pointers this way is error-prone. I’d recommend using the parsing facilities provided in the language, starting with strtok().