When I try to delete array pointer which declared like
short *width = NULL;
width = new short[lenght];
delete[] width;
the programs stop at delete part and returns a random number.
here is my all program
int main(){
short **junction = NULL, *width = NULL, length = 0;
ifstream input;
input.open("sample_input.txt");
if(!input)
cout << "No such a file named \"sample_input.txt\"" << endl;
else if(input >> length){
junction = new short*[length];
width = new short[length];
string str;
for(int i = 0; i - 1 < length && getline(input, str); i ){
istringstream ss(str);
width[i - 1] = (str.size() 1) / 2; //numbers can be two char, so in this case, here we allocate more than necessary memory
junction[i - 1] = new short[width[i - 1]];
for(int j = 0; j < width[i - 1]; j ){
if(ss.eof()){
junction[i - 1][j] = -1; // -1 is the key value of emtpy spaces
continue;
}
ss >> junction[i - 1][j];
}
}
}
input.close();
/*
for(int i = 0; i < length; i )
delete[] junction[i];
delete[] junction;
delete[] width;
*/
return 0;
}
the comment part makes problem, I tried those delete statements seperately just for part is runing but not as I expected here is my sample input:
CodePudding user response:
Your code should be actually fine. Please show us the whole program.
florian@florian-desktop:~$ cat -n test2.cpp
1 #include <iostream>
2 int main()
3 {
4 const int length = 4;
5 short *width = NULL;
6 width = new short[length];
7 delete[] width;
8 }
florian@florian-desktop:~$ valgrind ./a.out
==22630== Memcheck, a memory error detector
==22630== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==22630== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==22630== Command: ./a.out
==22630==
==22630==
==22630== HEAP SUMMARY:
==22630== in use at exit: 0 bytes in 0 blocks
==22630== total heap usage: 2 allocs, 2 frees, 72,712 bytes allocated
==22630==
==22630== All heap blocks were freed -- no leaks are possible
==22630==
==22630== For lists of detected and suppressed errors, rerun with: -s
==22630== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Valgrind shows that all reserved memory is correctly released.
-- Updated:
I corrected your full code:
#include <iostream>
#include <sstream>
#include <fstream>
using namespace std;
int main() {
short **junction = NULL, *width = NULL, length = 12;
ifstream input;
input.open("sample_input.txt");
if(!input)
cout << "No such a file named \"sample_input.txt\"" << endl;
else if(input >> length){
junction = new short*[length];
width = new short[length];
string str;
for(int i = 0; i < length && getline(input, str); i ){
istringstream ss(str);
width[i] = (str.size() 1) / 2; //numbers can be two char, so in this case, here we allocate more than necessary memory
junction[i] = new short[width[i]];
for(int j = 0; j < width[i]; j ){
if(ss.eof()){
junction[i][j] = -1; // -1 is the key value of emtpy spaces
continue;
}
ss >> junction[i][j];
}
}
}
input.close();
for(int i = 0; i < length; i )
delete[] junction[i];
delete[] junction;
delete[] width;
return 0;
}