10
39.0 13.0 68.0 15.0 10.0 20.0 31.0 15.0 41.0 16.0
42.0 12.0 45.0 5.0 2.0 61.0 89.0 32.0 47.0 18.0
I typed in a number, but I couldn't read it.
By the way, I did the following program.
#include<stdio.h>
# include <string.h>
# include <stdlib.h>
constint NMOJI=50;
constint MAX_ITEM=100;
int main()
{
FILE*fp;
inti,j;
intitem;
double capacity;
double weight [MAX_ITEM], value [MAX_ITEM];
char file_name [NMOJI];
printf("Data Fly Name:");
scanf("%s", file_name);
if(((fp=fopen(file_name, "r"))==NULL){
printf("%s: The file cannot be opened.\n", file_name);
return-1;
}
printf("Knapsack capacity:"; scanf("%lf", & capacity);
printf("data filename:%s\n", file_name);
printf("nappack capacity: %f\n", capacity);
printf("\n");
fscanf(fp, "%d", & nitem);
if(nitem>MAX_ITEM){
printf("Please set the number of items to %3d or less.\n", MAX_ITEM);
return-1;
}
for (i=0; i<nitem;i++)
fscanf(fp, "%lf", & weight[i]);
for (i=0; i<nitem;i++)
fscanf(fp, "%lf", & value[i]);
fclose(fp);
return 0;
}
where fscanf(fp, "%d", &nitem); the top 10 is
for (i=0; i<nitem;i++)
fscanf(fp, "%lf", & weight[i]);
for (i=0; i<nitem;i++)
fscanf(fp, "%lf", & value[i]);
So, I thought I could read the weight of the second level from the top and the value of the bottom, but somehow the result was
$./a.out
Data Fly Name: knap10.txt
Knapsack capacity: 121
Data File Name: knap10.txt
Knapsack Capacity: 121.000000
It only appears.I thought the fscanf function was to read the characters in the file, so I didn't know what was wrong.Why can't I read the numbers in the file?
c
Perhaps the file loading was successful.It is normal to end with the line "Napsack Capacity" because nothing is displayed after a successful load.
In order to determine if the load was successful, why don't you modify the code as follows?
if(fscanf(fp, "%d", &nitem)!=1){
fprintf(stderr, "Number of items could not be read\n";
return EXIT_FAILURE;
}
if(nitem>MAX_ITEM){
fprintf(stderr, "Please keep item count below %3d.\n", MAX_ITEM);
return EXIT_FAILURE;
}
for(i=0;i<nitem;i++){
if(fscanf(fp, "%lf", & weight[i])!=1){
fprintf(stderr, "%dth weight value could not be read.\n", i+1);
return EXIT_FAILURE;
}
}
for(i=0;i<nitem;i++){
if(fscanf(fp, "%lf", & value[i]))!=1){
fprintf(stderr, "%dth value value could not be read.\n", i+1);
return EXIT_FAILURE;
}
}
fclose(fp);
printf("%d Item Load Completed.\n",nitem);
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