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ENGR 0012 – Dr. Lund’s 10am Section
March 20, 2007
• Section 5.5
Reading data from a file
(See Ex1.cpp, Ex2.cpp, Ex3.cpp)
Inputting data from a file - Summary
Inputting data from a file requires 4 primary
statements:
1. Declaration of file pointer variable:
FILE *file_ptr
2. Opening file:
file_ptr = fopen(“filename”, “r”);
3. Reading file data:
fscanf(file_ptr , “formatting”, &variable)
4. Closing file (Clears buffer of file info):
fclose(file_ptr);
#include <stdio.h>
main()
{double col2;
int r1c1, r2c1;
FILE *data1;
data1=fopen("stats.txt","r");
fscanf(data1, "%d", &r1c1);
fscanf(data1, "%d; %lf", &r2c1, &col2);
printf("r1c1 = %d\nr2c1 = %d\ncol2 = \
%lf\n\n", r1c1, r2c1, col2);
fclose(data1);
}
Note that the formatting string for fscanf
requires knowledge of the formatting of
the data in the file, i.e. what separates
the values, what kind of values, etc.
