2.1.c

#include <stdio.h>

int main(void) {
	
	printf("Gustav Mahler\n");
	printf("Gustav\nMahler\n");
	printf("Gustav ");
	printf("Mahler");
	
	return 0;
}

2.2.c

#include <stdio.h>

int main(void) {
	
	printf("name: Gustav Mahler\n");
	printf("address: China\n");
	
	return 0;
}

2.3.c

#include <stdio.h>
#define YEAR_PER_DAY 365

int main(void) {
	
	int age, days;
	age = 18;
	days = age * YEAR_PER_DAY;
	printf("age:%d\n", age);
	printf("days:%d\n", days);
	
	return 0;
}

2.4.c

#include <stdio.h>

void jolly(void);
void deny(void);

int main(void) {
	
	jolly();
	jolly();
	jolly();
	deny();
	
	return 0;
}

void jolly(void) {
	printf("For he's a jolly good fellow!\n");
}

void deny(void) {
	printf("Which nobody can deny!\n");
}

2.5.c

#include <stdio.h>

void br(void);
void ic(void);

int main(void) {
	
	br();
	printf(", ");
	ic();
	printf("\n");
	ic();
	printf(",\n");
	br();
	
	return 0;
}

void br(void) {
	printf("Brazil, Russia");
}

void ic(void) {
	printf("India, China");
}

2.6.c

#include <stdio.h>

int main(void) {
	
	int toes;
	toes = 10;
	printf("toes = %d\n", toes);
	printf("toes * 2 = %d\n", toes * 2);
	printf("toes ^ 2 = %d\n", toes * toes);
	
	return 0;
}

2.7.c

#include <stdio.h>

void smile(void);

int main(void) {
	
	smile();
	smile();
	smile();
	printf("\n");
	smile();
	smile();
	printf("\n");
	smile();
	printf("\n");
	
	return 0;
}

	void smile(void) {
		printf("Smile!");
	}

2.8.c

#include <stdio.h>

void one_three(void);
void two(void);

int main(void) {
	
	printf("starting now:\n");
	one_three();
	printf("done!\n");
	
	return 0;
}

void one_three(void) {
	printf("one\n");
	two();
	printf("three\n");
}

void two(void) {
	printf("two\n");
}