Why, when reading a file, does it not write values ​​after processing?

Question

C++ / C#

There is code that reads incoming values.

#include <stdio.h>

int main(){
    char city[80];
    char index[80];
    int started = 0;
    
    puts("data=[");
    while(scanf("%79,%79[^\n]", city, index)==2){
        if(started){
            printf(",\n");
        }
        else{
            started = 1;
        }
        printf("{CITY = %s   INDEX = %s}", city, index);
    }
    printf("\n]");
    return 0;
}

There is a file with values ​​that need to be converted to another format.

Moscow,RU
London,EN
Minsk,BY

After the command in the console.
test < city.txt > outfile.txt
I get a file without values:

data=[

]

What could be the reason?

Answer 1

Try the following expression in scanf:
scanf("%79[^,],%79[^\n]\n", city, index)
the first [^,] means to read until a comma is encountered, the second comma is to skip the comma character . A similar situation with \n.