Question

I am trying to read in from a file, and I can’t get the pattern of it right. Can someone tell me what I can do to get it working?

int main()
{

char name[20];
int age;
float highbp, lowbp, risk;
FILE *fp;
fp = fopen("data.dat", "r");

if(fp == NULL){

    printf("cannot open file\n\n");

}

while(fscanf(fp, "name:%s\nage:%d\nbp:%f\nrisk:%f", name, &age, &highbp, &risk) != EOF){


}
printf("Name: %s\n", name);
printf("%d\n", age);
printf("%f\n", highbp);
printf("%f\n", risk);

}

data.dat:

name:tom
age:32
bp:43.00
risk:0.0

Answer 1

If it can’t open the file it prints a message, but then continues. Instead it should return from main.

if (fp == NULL) {
    printf("cannot open file\n\n");
    return 1;
}

fscanf will return the number of items parsed, so it’s probably safer to stop reading when the number returned < 4 (not all the items could be read).

Presumably “data.dat” contains multiple records and each line has a line ending. This means that after reading the first record the next character in the file is the line ending for the “risk:0.0” line. You should end the fscanf template with \n.

This is because the second time it tries to parse the file, fscanf will see that character, which it isn’t expecting (the fscanf template starts “name:”), so it will stop reading, and you’ll get only the first record.