Currently, I have some confusion in realloc an array string. If I have this:
char** str = (char**)malloc(100*sizeof(char*));
str[0] = (char*)malloc(sizeof(char)*7); //allocate a space for string size 7
//some other code that make the array full
My question is, if I want to realloc str[0] to size 8, do I need to realloc both str and str[0] like this:
str = (char**)realloc(str,sizeof(char*)*101);
str[0] = (char*)realloc(str[0],sizeof(char)*8);
Is this correct?
You realloc the master array when you want to add a string (changing the number of strings). You realloc an individual string when you want to change that string's length.
Therefore, only realloc str[0] if you want to change the string's buffer size.
No, you do not need to reallocate the array of strings to lengthen the string at index zero. All you need is
str[0] = (char*)realloc(str[0],sizeof(char)*8);
str array contains the string pointers - all 100 of them. The individual strings are allocated separately; the pointers to these strings are stored inside str. If you need more than 100 strings, you need to realloc() the str; if you need to increase the length of an individual string, you realloc() a str[i].