[c] How do I properly 'printf' an integer and a string in C?

I have the following code:

char *s1, *s2;
char str[10];

printf("Type a string: ");
scanf("%s", str);

s1 = &str[0];
s2 = &str[2];

printf("%s\n", s1);
printf("%s\n", s2);

When I run the code, and enter the input "A 1" as follow:

Type a string: A 1

I got the following result:


I'm trying to read the first character as a string and the third character as an integer, and then print those out on the screen. The first character always works, but the screen would just display random stuffs after that.... How should I fix it?

This question is related to c string input printf

The answer is

You're on the right track. Here's a corrected version:

char str[10];
int n;

printf("type a string: ");
scanf("%s %d", str, &n);

printf("%s\n", str);
printf("%d\n", n);

Let's talk through the changes:

  1. allocate an int (n) to store your number in
  2. tell scanf to read in first a string and then a number (%d means number, as you already knew from your printf

That's pretty much all there is to it. Your code is a little bit dangerous, still, because any user input that's longer than 9 characters will overflow str and start trampling your stack.

Try this code my friend...

int main(){
   char *s1, *s2;
   char str[10];

   printf("type a string: ");
   scanf("%s", str);

   s1 = &str[0];
   s2 = &str[2];

   printf("%c\n", *s1);   //use %c instead of %s and *s1 which is the content of position 1
   printf("%c\n", *s2);   //use %c instead of %s and *s3 which is the content of position 1

   return 0;

scanf("%s",str) scans only until it finds a whitespace character. With the input "A 1", it will scan only the first character, hence s2 points at the garbage that happened to be in str, since that array wasn't initialised.

Examples related to c

conflicting types for 'outchar' Can't compile C program on a Mac after upgrade to Mojave Program to find largest and second largest number in array Prime numbers between 1 to 100 in C Programming Language In c, in bool, true == 1 and false == 0? How I can print to stderr in C? Visual Studio Code includePath "error: assignment to expression with array type error" when I assign a struct field (C) Compiling an application for use in highly radioactive environments How can you print multiple variables inside a string using printf?

Examples related to string

How to split a string in two and store it in a field String method cannot be found in a main class method Kotlin - How to correctly concatenate a String Replacing a character from a certain index Remove quotes from String in Python Detect whether a Python string is a number or a letter How does String substring work in Swift How does String.Index work in Swift swift 3.0 Data to String? How to parse JSON string in Typescript

Examples related to input

Angular 4 - get input value React - clearing an input value after form submit Min and max value of input in angular4 application Disable Button in Angular 2 Angular2 - Input Field To Accept Only Numbers How to validate white spaces/empty spaces? [Angular 2] Can't bind to 'ngModel' since it isn't a known property of 'input' Mask for an Input to allow phone numbers? File upload from <input type="file"> Why does the html input with type "number" allow the letter 'e' to be entered in the field?

Examples related to printf

How I can print to stderr in C? How can you print multiple variables inside a string using printf? Unsigned values in C How to print multiple variable lines in Java Scanf/Printf double variable C Format specifier %02x %i or %d to print integer in C using printf()? What is the printf format specifier for bool? printf() prints whole array Printf width specifier to maintain precision of floating-point value