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C program to input student details in a file, save and extract them as records

This program is asked by Sam Atkinson Amerity through comment on 14/12/2016.

Question

HI I have got assignment to write a program in c , it is like a grade convener to alphabet the input must be name subject score and grade until the end of input,1. with E0F / ctrl z. the output must be number name subject score grade . print the position who gets A . and 2. from table number 1 short it from the lowest score and then print the position of a . 3 short from the name of student and print the position who got A.

Answer

Here, we are reading records just like file input and saving them into a file, file is terminating by pressing ‘#’ character.

To extract records, we are reading character by character and putting them into a string as we found new line character value (0xA) – that will be the complete one record and so on...

#include <stdio.h>

#define SIZE 1024

int main()
{
    char text[SIZE]={0},record[100];
	char ch;
	int  cnt=0,len;
	FILE *fp; /*file pointer*/

/*create file*/
	fp=fopen("file1.txt","w");
	
	if(fp==NULL)
	{
		printf("Error in creating file");
		return -1;
	}
	
	printf("Enter student details line wise (press # to save and close):\n");
	while(1)
	{
		ch=getchar();
		if(ch=='#')
		{
			break;
		}
		fputc(ch,fp);
	}
	fclose(fp); //close the file
	printf("File saved successfully\n");
	
	/*open file*/
	fp=fopen("file1.txt","r");
	if(fp==NULL)
	{
		printf("Error in opening file.\n");
		return -1;
	}

	printf("Entered records are:\n");
	//read content from file
	cnt=0;
    while((ch=fgetc(fp))!=EOF)
	{
		if(ch==0x0A)//check new line
		{
			record[cnt++]='\0';
			cnt=0;
			printf("%s\n", record);
			continue;
		}
		record[cnt++]=ch;
    }	
	fclose(fp);
	return 0;
}

Output

Enter student details line wise (press # to save and close):
ABC 80 A
PQR 90 A
XYZ 70 B
# 
File saved successfully 
Entered records are:
ABC 80 A
PQR 90 A
XYZ 70 B 

How to extract values from this record

Since file is not written through a structure (file contains characters), that’s why we separated each value through space

Let suppose one record (with name, subject score and grade) is:

ABC 80 A

Consider the following code to extract values from this string

#include <stdio.h>

int main()
{
	char record[]="ABC 80 A";
	char name[30]; 
	int score;
	char grade;
	
	sscanf(record,"%s %d %c",name,&score,&grade);
	
	printf("Name: %s\n",name);
	printf("Subject score: %d\n",score);
	printf("Grade: %c\n",grade);
	
	return 0;
}

Output

    Name: ABC 
    Subject score: 80 
    Grade: A