Cutting a string into pieces - c++

Question

How can I extract pieces from this string?
I have a file that contains:
0065445 APPLE$456
089464 MANGO$489
0012389 GUAVA$744
What I want to do is input the file line by line, then cut the string into some pieces.
0065455 Will go in a struct a[0].num
APPLE will go in struct a[0].name
456 will go in struct a[0].dollar
And similarly for other lines.
Everything is working fine, but it's not successfully getting the dollar part into its variable.
Here's the code:
#include<cstdlib>
#include<iostream>
using namespace std ;
int main(){
FILE *fp;
fp = fopen("input.txt","r");
char str[80] ;
struct abc{
int num;
char name[20];
int dollar;
};
int i = 0;
while(fgets(str,79,fp)!=NULL){
struct abc a[i] ;
sscanf(str,"%d %[^$]s$%d\n",&a[i].num,a[i].name,&a[i].dollar);
cout <<i+1 <<") Number : "<<a[i].num<<" Name : "<< a[i].name <<" Dollar : "<< a[i].dollar << endl ;
i++;
}
return 0 ;
}
/* These didn't work too.
sscanf(str,"%d %[^$]s %d\n",&a[i].num,a[i].name,&a[i].dollar);
sscanf(str,"%d %[^$]s%d\n",&a[i].num,a[i].name,&a[i].dollar);
sscanf(str,"%d %s$%d\n",&a[i].num,a[i].name,&a[i].dollar);
*/
There's 1 more problem: the first part of string is an int that starts with 0, but the zero is not being accepted in the int. How to do it?
This is working as I want now but still after parasing the string into an int I am not getting the zeroes:
#include<cstdlib>
#include<iostream>
#include<cstring>
using namespace std ;
int main(){
FILE *fp;
fp = fopen("input.txt","r");
char str[80] ;
char temp[80] ;
struct abc{
int num;
char name[20];
int dollar;
};
int i = 0;
int j = 0 ;
while(fgets(str,79,fp)!=NULL){
i = 0;
j = 0 ;
struct abc a[i] ;
char* ptr = 0; // this is used as a helper variable to strtok
ptr = strtok(str, " $\n"); // we specify the delimiters here
while (ptr != NULL)
{
if (j == 0){
strcpy(temp, ptr);
a[i].num = atoi(temp);
}
if (j == 1)
strcpy(a[i].name, ptr);
if (j == 2){
strcpy(temp, ptr);
a[i].dollar = atoi(temp);
}
ptr = strtok(NULL, " $\n");
j++;
}
cout <<i+1 <<") Number : "<<a[i].num<<" Name : "<< a[i].name <<" Dollar : "<< a[i].dollar << endl ;
i++;
}
return 0 ;
}
/* These didn't work either.
sscanf(str,"%d %[^$]s %d\n",&a[i].num,a[i].name,&a[i].dollar);
sscanf(str,"%d %[^$]s%d\n",&a[i].num,a[i].name,&a[i].dollar);
sscanf(str,"%d %s$%d\n",&a[i].num,a[i].name,&a[i].dollar);
*/

Answer 1

Based on the C++ tag, I'd do things a little differently. First I'd overload the stream extractor operator for your abc type:
std::istream &operator>>(std::istream &is, abc &a) {
is >> a.num;
std::getline(is, a.name, '$');
return is >> a.dollar;
}
Then you can use that to read in a file of records, such as:
abc temp;
std::vector<abc> a;
std::ifstream in("input.txt");
while (in >> temp)
a.push_back(temp);
Or, you can use an istream_iterator to initialize a vector directly from the stream:
std::vector<abc> a((std::istream_iterator<abc>(in)),
std::istream_iterator<abc>());
The easiest way to keep the leading zeros on the first number is probably to change it from an int to a std::string.

Answer 2

Use strtok:
Here is a simple code (C only) that prints your strings separately (I recommended a similar solution in another post).
#include <stdio.h>
#include <string.h> // for strcpy and strtok
#include <stdlib.h> // for atoi
int main()
{
char input [25] = "0065445 APPLE$4056"; // input string
// storage for the separate parts of the string
char line[10];
char fruit[10];
char number[10];
char* ptr = 0; // this is used as a helper variable to strtok
ptr = strtok(input, " $\n"); // we specify the delimiters here
int i = 0;
// I'm using i here as a control variable so that during each iteration different part
// of the string is saved
while (ptr != NULL)
{
if (i == 0)
strcpy(line, ptr);
if (i == 1)
strcpy(fruit, ptr);
if (i == 2)
strcpy(number, ptr);
ptr = strtok(NULL, " $\n");
i++;
}
printf("%s %s %s\n", line, fruit, number);
return 0;
}
Some sample output:
$ ./a.out
0065445 APPLE 4056
Is this what you need?

Answer 3

the 0's will not show up when you print the integer a[i].num.
You could make a[i].num a string (char[]) or an integer array. to make the 0's show up. you can parse it as an integer (via atoi(str)), if you need it to be used otherwsie.

Answer 4

#include <iostream>
#include <fstream>
#include <sstream>
struct abc{ int num; std::string name; int dollar; };
int main(int argc, char* argv[]) {
std::ifstream file("input");
abc st1;
std::string l;
while (file >> st1.num >> l) {
if (size_t p = l.find_first_of('$')) {
st1.name = l.substr(0, p);
std::istringstream(l.substr(p+1)) >> st1.dollar;
std::cout << st1.num << " : "
<< st1.name << " : " << st1.dollar << std::endl;
}
}
return 0;
}