IN C-PROGRAMMING:
What is Structured Programming; what is machine and assembly coding; what is pseudo coding?
What do the following do: compiler, preprocessor, return 0, { }?
Describe data types and what distinguishes each; how would one combine data types?
Explain functions and what are they for?
Explain: scanf (gets, fgets, getchar, fgetchar), printf( puts, fputs, putchar, fpetchar)
What do the following mean: strlen, strcmp, strcat, strcpy?
What does fopen and fclose mean?
Explain the difference between stdin and file.
What if your file is not read or opened? What is likely the problem?
Explain bubble sort.
What do we use an editor versus word for example?
What are major decision processes: IF, IF/ELSE, SWITCH, ||, &&.
What is assignment and what is the distinction between it and typical arithmetic operations?
How does one construct a loop?
What is the difference between a global and a local declaration?
What is a key feature that ends a statement?
What is an array?
What is a pointer?
What is pass by value and pass by reference?
How does one read, write or append a file?
Q) How does one read, write or append a file?
Answer:
Reading data from a File
There are three different functions dedicated to reading data from a file
The following program demonstrates reading from fputs_test.txt file using fgets(),fscanf() and fgetc () functions respectively :
#include <stdio.h> int main() { FILE * file_pointer; char buffer[30], c; file_pointer = fopen("fprintf_test.txt", "r"); printf("----read a line----\n"); fgets(buffer, 50, file_pointer); printf("%s\n", buffer); printf("----read and parse data----\n"); file_pointer = fopen("fprintf_test.txt", "r"); //reset the pointer char str1[10], str2[2], str3[20], str4[2]; fscanf(file_pointer, "%s %s %s %s", str1, str2, str3, str4); printf("Read String1 |%s|\n", str1); printf("Read String2 |%s|\n", str2); printf("Read String3 |%s|\n", str3); printf("Read String4 |%s|\n", str4); printf("----read the entire file----\n"); file_pointer = fopen("fprintf_test.txt", "r"); //reset the pointer while ((c = getc(file_pointer)) != EOF) printf("%c", c); fclose(file_pointer); return 0; }
Writing to a File
In C, when you write to a file, newline characters '\n' must be explicitly added.
The stdio library offers the necessary functions to write to a file:
The program below shows how to perform writing to a file:
fputc() Function:
#include <stdio.h> int main() { int i; FILE * fptr; char fn[50]; char str[] = "Guru99 Rocks\n"; fptr = fopen("fputc_test.txt", "w"); // "w" defines "writing mode" for (i = 0; str[i] != '\n'; i++) { /* write to file using fputc() function */ fputc(str[i], fptr); } fclose(fptr); return 0; }
If we open the file in "a" mode instead of "w", we can append to the file.
Q) What is pass by value and pass by reference?
Answer:
By definition, pass by
value means you are making a copy in memory of the actual
parameter's value that is passed in, a copy of the contents of the
actual parameter. Use pass by value when when you are only "using"
the parameter for some computation, not changing it for the client
program.
In pass by reference
(also called pass by address), a copy of the address of the actual
parameter is stored. Use pass by reference when you are changing
the parameter passed in by the client program.
Consider a swapping function to demonstrate pass by value vs. pass
by reference. This function, which swaps ints, cannot be done in
Java.
main() { int i = 10, j = 20; swapThemByVal(i, j); cout << i << " " << j << endl; // displays 10 20 swapThemByRef(i, j); cout << i << " " << j << endl; // displays 20 10 ... } void swapThemByVal(int num1, int num2) { int temp = num1; num1 = num2; num2 = temp; } void swapThemByRef(int& num1, int& num2) { int temp = num1; num1 = num2; num2 = temp; }
Q) What is a pointer?
Answer:
A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant, you must declare a pointer before using it to store any variable address. The general form of a pointer variable declaration is −
type *var-name;
Here, type is the pointer's base type; it must be a valid C data type and var-name is the name of the pointer variable.
Q) What is an array?
Answer:
Arrays a kind of data structure that can store a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.
NOTE: As per Chegg policy, I am allowed to answer only 4 questions (including sub-parts) on a single post. Kindly post the remaining questions separately and I will try to answer them. Sorry for the inconvenience caused.
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