What is main in C
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Definition: main() is a predefined function in C, serving as the entry point for program execution.
Role: It starts and ends the execution of a C program.
Return Type: main() can have a return type of int or void.
Parameters: Can be written with or without parameters depending on the requirement of the program.
Importance of main() Function:
Entry Point: Operating systems call main() to execute C programs.
Universal: It's a universally accepted keyword in C.
User-defined: It's a user-defined function; parameters can be passed based on program requirements.
Runtime Invocation: Code inside main() runs at runtime, not compile time.
Syntax of main() in C
int main() { // code here return 0; }
OR
void main() { // code here }
Types of main()
void main():
Does not return any value.
Used when no value needs to be returned.
void main() { // code here }
int main():
Returns an integer value.
Should have a return 0; statement at the end.
int main() { // code here return 0; }
int main(int argc, char *argv[]):
Accepts command-line arguments.
int main(void):
Similar to int main(), but explicitly states no parameters.
int main(void) { // code here return 0; }
void main(void):
Does not return any value and doesn't take any arguments.
void main(void) { // code here }
Examples:
Simple main() without arguments:
// Program for Simple main() without arguments #include<stdio.h>void main() { printf("C Programming"); }
Output:
C Programming
main() with nested functions:
// Program for main() function with nested functions #include<stdio.h>void fun1() { printf("It is a second function."); } int main() { printf("It is a main() function\n"); fun1(); return 0; }
Output:
It is a main() function. It is a second function.
Return Value: Use return 0; or EXIT_SUCCESS to indicate successful execution.
EXIT_FAILURE can be used for unsuccessful termination.
Avoid void main(): Though some compilers allow void main(), it's not standard and can lead to undefined behavior.
This overview provides a solid understanding of the main() function in C, its types, and usage.
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