[SOLVED] Trigger the invocations of system call in Linux, C program?

Issue

When the below C program is run in a Linux,the execution of which line must trigger invocation of system call, why? What is invocation of system call ?

void main()
{
    double x=1;
    double y;
    double *z;

    z=(double *)malloc(sizeof(double)); // line 1
    scanf("%f", &y);                    // line 2
    *z=sqrt(y);                         // line 3
    y=y*2.0;                            // line 4
    printf("y=%f, *z=%f\n", y, *z);     // line 5
    y=y/x;                              // line 6 
    printf("y=%f",y);                   // line 7
}

Solution

A call to malloc invokes a system call because the operating system manages the memory.

Calls to scanf and printf invoke system calls because the operating system manages i/o operations.

Invocation of a system call is a call for an operating system service.

Answered By - gmoshkin