Connection string-sprintf

In writing a program, you sometimes need to connect two strings. Here we will introduce two functions.
Function 1: sprintf

Reference: http://oss.lzu.edu.cn/blog/article.php? Tid_877.html

Definition:
Int sprintf (char * buffer, const char * Format [, argument]...);

Description:
Sprintf is a variable parameter function. Apart from the first two parameter types, sprintf can take over multiple parameters.
Its essence is obviously on the second parameter: Format String.

Return Value: Some people pay less attention to the return value of the printf/sprintf function, but sometimes it is useful. spritnf returns the number of characters that the function call finally prints to the character buffer.
That is to say, after a sprinf call ends, you do not need to call strlen again to know the length of the result string.

The usage is as follows:

1. Print the integer to the string:
One of the most common applications of sprintf is to print Integers to strings. Therefore, spritnf can replace ITOA in most cases.
For example:
// Print the integer 123 into a string and save it in S.

Sprintf (S, "% d", 123); // generate "123"

2. connection string
Since the sprintf format control string can insert a variety of things and finally "connect them into a string", it can naturally connect strings,
This can replace strcat in many cases, but sprintf can connect multiple strings at a time (it can also insert other content in them at the same time, in short, it is very flexible ).
For example:

Char * Who = "I ";

Char * Whom = "csdn ";

Sprintf (S, "% s love % S.", who, whom); // generate: "I love csdn ."

Here are two sprintf examples:
Example 1:
Main ()
{
Int I = 0;
Char * B = "Link ";
// Char s [10];
Char * s;
S = (char *) malloc (10 );
For (I = 0; I <5; I ++ ){
Sprintf (S, "% S % d", B, I );

Printf ("% s/n", S );
}
}

Output result:
Link0
Link1
Link2
Link3
Link4

Example 2:
# Include <stdio. h>
# Include <time. h>
# Include <stdlib. h>
Int main (){
Srand (time (0 ));
Char s [64];
Int offset = 0;
Int I = 0;
For (I = 0; I <10; I ++ ){
Offset + = sprintf (S + offset, "% d,", Rand () % 100); // the return value of the sprintf function is the length of the array, which is equivalent to the value of strlen.
}
S [offset-1] = '/N'; // Replace the last comma with a line break.
Printf ("the result is: % s/n", S );
Return 0;
}

Output result:
The result is :,

Function 2:

Function Name: strcat
Function: String concatenation Function
Usage: char * strcat (char * Destin, char * Source );
Program example:
# Include <stdio. h>
# Include <stdlib. h>
# Include <string. h>
Main ()
{Char str1 [30] = "ABCDE", str2 [10] = "123 ";
Strcat (str1, str2 );
Printf ("the merge result is: % s/n", str1 );
}

Output result:
The merge result is: abcde123

Differences:
Since the sprintf format control string can insert a variety of things and finally "connect them into a string", it can naturally connect strings,
This can replace strcat in many scenarios, but sprintf can connect multiple strings at a time (it can also insert other content in them at the same time, in short, it is very flexible)