从文本文件中读取并总结第一个单词相同的行

Question

I have a text file with such information:

CD-R 50
DVD-R 20
CD-R 15
BINDERS 30
RADIO 35
CD-R 100

I have to read that text file and sum the same products. Output Should be like that

CD-R 165
DVD-R 20
BINDERS 30
RADIO 35

Here is my code:

#include <stdlib.h>
#include <stdio.h>
int main(){
FILE *f = fopen("file.txt","r")
char str[100];
int arr[100];
int entity;
int products = 6,i;
for(i=0;i<products;i++){
fscanf(f,"%s %d",na[i],&entity);
arr[i]=entity;
}
    int count=1;
    for(i=0;i<prod;i++){
        for(j=i+1;j<prod;j++){
            if(strcmp(na[i],na[j])==0){
                arr[i]+=arr[j];
            }
        }
    }
}

so I read every line without any problem and put each name and entity in character and integer array, then I count distinct product names. Then i want to to print output as shown above but I find it difficult could use little hint.

Answer 1

As you asked for hints, I will not provide a full solution.

1. You are dealing with a combination of name and values. Therefore you should drop your separate arrays and use a struct that combines name and number. Then create an array for that struct.

#define MAX_NAME     100
#define MAX_PRODUCTS  10
typedef struct product
{
  char product_name[MAX_NAME]
  int  number;
} product;

product products[MAX_PRODUCTS];

2. You are dealing with an unsorted file that contains multiple lines with same product name which you want to combine to one entry.
   Instead of reading directly into your array, read each line into a temp buffer first. Then check if you already have the same product in your array. Depending on that, either add new product to your array or add the new number to the old entry in the array.

3. Afterwards print all entries in your array.

4. It is not clear if you can know in advance how many different entries you can have in your file. If you cannot know it, you might switch from that array to a dynamically allocated buffer that is (re)allocated with proper size.