Table of contents title
Parsing C language strcmp function prototype
1 Introduction
In C language, strcmpfunction is a very commonly used function that is used to compare whether two strings are equal. This function <string.h>is defined in the library. As Bjarne Stroustrup said in "The C++ Programming Language": "Understanding the standard library is key to becoming proficient in C and C++." 1 Understanding the standard library is the key to mastering C and C++.
2. Function prototype
In C language, strcmpthe prototype of a function is as follows:
int strcmp(const char *str1, const char *str2);
- Function Prototype :
int strcmp(const char *str1, const char *str2);
This function accepts two strings (character pointers) as parameters and returns an integer. The meaning of the return value is as follows:
- Return value less than 0:
str1less thanstr2 - The return value is equal to 0:
str1equal tostr2 - The return value is greater than 0:
str1greater thanstr2
3. Underlying implementation
3.1 Source code analysis
strcmpFunctions are usually implemented in the GNU C Library (glibc). The specific document is string/strcmp.c.
int strcmp (const char *p1, const char *p2)
{
const unsigned char *s1 = (const unsigned char *) p1;
const unsigned char *s2 = (const unsigned char *) p2;
unsigned char c1, c2;
do
{
c1 = (unsigned char) *s1++;
c2 = (unsigned char) *s2++;
if (c1 == '\0')
return c1 - c2;
}
while (c1 == c2);
return c1 - c2;
}
- Source Code : Implemented in files of GNU C Library (glibc)
string/strcmp.c.
3.2 Algorithm analysis
This function uses a do-whileloop to compare two strings character by character. The loop ends when an unequal character or the string terminator ( \0) is encountered.
4. Deep insights into thinking and being
When we delve into strcmpthe implementation details, we can't help but ask, why is it designed this way? This reflects a way of thinking that pursues efficiency and simplicity. This way of thinking is reflected in many aspects. For example, when solving problems, we often need to find the most direct and simple method without losing accuracy.
5. Summary
strcmpFunction is a very basic but crucial function in C language. By in-depth understanding of its underlying implementation, we can not only improve our programming skills, but also allow us to better understand the thinking behind it.
| angle | describe |
|---|---|
| function prototype | int strcmp(const char *str1, const char *str2); |
| underlying implementation | do-whileCompare characters one by one through a loop |
| way of thinking | Pursue efficiency and simplicity |
6. Code examples
To better understand strcmphow the function works, here is a simple code example.
#include <stdio.h>
#include <string.h>
int main() {
char str1[] = "Hello";
char str2[] = "World";
char str3[] = "Hello";
int result;
// Comparing str1 and str2
result = strcmp(str1, str2);
printf("strcmp(str1, str2) = %d\n", result);
// Comparing str1 and str3
result = strcmp(str1, str3);
printf("strcmp(str1, str3) = %d\n", result);
return 0;
}
- Code Example : This code shows how to use
strcmpfunctions for string comparison.
In this example, strcmp(str1, str2)a negative number will be returned because str1lexicographically less than str2. Instead, strcmp(str1, str3)0 will be returned, indicating that the two strings are equal.
7. Summary and outlook
strcmpFunction is a very basic but powerful function. Its implementation reflects the pursuit of efficiency and simplicity of programming thinking. By gaining a deeper understanding of this function, we can not only improve our programming skills but also better understand this way of thinking.
| angle | describe |
|---|---|
| function prototype | int strcmp(const char *str1, const char *str2); |
| underlying implementation | do-whileCompare characters one by one through a loop |
| way of thinking | Pursue efficiency and simplicity |
This article is strcmpa comprehensive analysis of functions, I hope it will be helpful to you. If you have more questions or need further explanation, please feel free to ask.
“The only way to learn a new programming language is by writing programs in it.” - Dennis Ritchie2
Conclusion
In our programming learning journey, understanding is an important step for us to move to a higher level. However, mastering new skills and ideas always requires time and persistence. From a psychological point of view, learning is often accompanied by constant trial and error and adjustment, which is like our brain gradually optimizing its "algorithm" for solving problems.
This is why when we encounter mistakes, we should view them as opportunities to learn and improve, not just as annoyances. By understanding and solving these problems, we can not only fix the current code, but also improve our programming skills and prevent making the same mistakes in future projects.
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