#include <stdio.h>
#include <stdlib.h>
#include "libxl.h"

int main()
{
    int numCustomers = 0;
    double sales = 0.0;
    double average = 0.0;

    // read input from user
    while (1) {
        double input;
        printf("Enter sales amount (0 to quit): ");
        scanf("%lf", &input);
        if (input == 0) {
            break;
        }
        sales += input;

        printf("Enter number of customers: ");
        scanf("%d", &numCustomers);
        average = sales / numCustomers;
    }

    // create a new Excel workbook and sheet
    BookHandle book = xlCreateBook();
    SheetHandle sheet = xlBookAddSheet(book, "Daily Report", NULL);

    // create a header row
    xlSheetWriteStr(sheet, 0, 0, "Daily Report", NULL);
    char date[20];
    time_t now = time(NULL);
    strftime(date, 20, "%Y-%m-%d", localtime(&now));
    char header[100];
    sprintf(header, "for %s", date);
    xlSheetWriteStr(sheet, 0, 1, header, NULL);

    // create a row for the data
    xlSheetWriteStr(sheet, 1, 0, "Date", NULL);
    xlSheetWriteNum(sheet, 1, 1, sales, NULL);
    xlSheetWriteNum(sheet, 1, 2, numCustomers, NULL);
    xlSheetWriteNum(sheet, 1, 3, average, NULL);

    // format the date column
    FormatHandle dateFormat = xlBookAddFormat(book, NULL);
    xlFormatSetNumFormat(dateFormat, XL_FORMAT_DATE_YYYYMMDD2);
    xlSheetSetCol(sheet, 0, 0, 12.0, NULL);
    xlSheetSetColFormat(sheet, 0, dateFormat);

    // format the header row
    FormatHandle headerFormat = xlBookAddFormat(book, NULL);
    xlFormatSetBold(headerFormat, 1);
    xlFormatSetFontName(headerFormat, "Arial");
    xlFormatSetFontSize(headerFormat, 14);
    xlSheetSetRowFormat(sheet, 0, headerFormat);

    // save and close the workbook
    xlBookSave(book, "DailyReport.xlsx");
    xlBookRelease(book);

    printf("Data written to DailyReport.xlsx\n");

    return 0;
}

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Read inputs from stdin

OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}