Output

In <stdio.h> there are several functions to print strings or characters to the STDOUT of the system

To see all the functions see here

In strings, escape characters can be used to print certain characters: - \n -> New Line - \t -> Tab - ' -> Single quote - " -> Double quote - \ -> Backlash

puts

Prints a string into the STDOUT and adds a \n character

puts("Hello");

printf

• More powerful than puts. Allows to print a formatted string (optional)
• Apart from the escape sequences, it also uses placeholders to format the string

printf("Hello"); // No formatting (but no \n at the end)

Placeholders

They are replaced in the strings with the parameters passed

Width and precision can also be modified with numbers and “.” among other things.

#include <stdio.h>
// Testing placeholders
int main(int argc, char const *argv[])
{
    int a = 2;
    float b = 3.85447995945454565; //large float
    printf("Printing integer %d, %i\n",a,a); //Printing integer 2, 2
    printf("Now printing a %s", "string\n"); //Now printing a string
    printf("Characters like %c as well\n", 'w'); //Characters like w as well
    printf("Whole float: %f, shortening %.2f, with width %5.2f\n",b,b,b); // Whole float: 3.854480, shortening 3.85, with width  3.85
    printf("Now scientific %e and the one that works both ways %.3g" ,b,b); //Here %.3g prints 3.85, with 2-> 3.9
    return 0;
}

For more information

putchar(int character)

• Method for outputting characters
• Works with int values for the characters (Unicode)
• Stream Oriented : Like getchar() is a buffered method, and only executes when the buffer is flushed or full

#include<stdio.h>
int main(int argc, char const *argv[])
{
    printf("Enter a character: ");
    int c = getchar();
    printf("Entered: ");
    putchar(c); //At the end flushes, and executes
    return 0;
}

Input

getchar()

• Reads a character from standard input
• Returns an int value for the character (Unicode)
• Stream Oriented

scanf()

• Uses placeholders (Like printf) to read values into declared variables
• Is used like scanf("format",&variable) using a pointer to the variable (address of operator)
• Not recommended for strings
• Stops reading in the first whitespace character

#include<stdio.h>
int main(int argc, char const *argv[])
{
    int a;
    float b;
    printf("Integer: ");
    scanf("%d",&a);
    printf("Decimal: ");
    scanf("%f",&b);
    printf("Entered int %d and float %.2f",a,b); //Can cut the float
    return 0;
}

fgets()

• Method normally used to read from streams (files for example)
• stdin is considered a stream in C, so is used to read strings
• Receives an input buffer, the max amount of bytes to read into the buffer and the stream

#include<stdio.h>
int main(int argc, char const *argv[])
{
    char string[64]; //Size for 63 char
    puts("Enter a string: ");
    fgets(string,64,stdin);
    printf("You entered %s",string);
    return 0;
}

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