C Standard I/O Legacy Methods

One can use c legacy io methods by importing the cstdio into the source file.

#include <cstdio>

0x00 Using Printf

printf is a stdout method used in C. Usage as following:

• Control Sequence First arg.
• Vars, Othervars.

Output	printf	cout
int	printf("%d", a)	cout << a
long	prinf("%d", a)	cout << a
float	printf("%f", f)	cout << a
double	printf("%lf", d)	cout << d
double (2 precision)	printf("%.2lf", d)	cout << fixed << setprecision(2) << d
char	print("%c", c)	cout << c
string	print("%s, s")	cout << s
mixed	print("Int %d, Float %f", a, b)	cout << << "Int " << a << ", Float " << b

#include <cstdio>

int main() {
    int i = 1;
    long l = 15342;
    float f = 2.1;
    double lf = 3.0012;
    char a = 't';
    printf("Hello World!\ni = %d, l = %ld, f = %.2f, lf = %lf, a = %c\n", i, l, f, lf, a);
    printf("Escaping sequence: \\\\n outputs \\n");
    return 0;
}

0x01 Using Scanf

scanf is a stdin method used in C. Usage is similar to printf, but characters other than control sequences are not allowed. Instead of variables accessede by control sequences, an address is needed to be passed in sinced the var needed to be passed in.

• Control Sequence First arg.
• Vars, Othervars. Need to be an address.

Output	printf	cout
int	scanf("%d", &a)	cin >> a
long	scanf("%d", &a)	cin >> a
float	scanf("%f", &f)	cin >> a
double	scanf("%lf", &d)	cin >> d
char	print("%c", &c)	cin >> c
string	print("%s, &s")	cin >> s
multiple vars	print("%d%f", &a, &b)	cin >> a >> b

#include <cstdio>

int main() {
    int a;
    printf("Input: ");
    scanf("%d", &a);
    printf("a = %d\n", a);
}

Both methods allow for standard escape sequences like \n