How to take a string in a specified position in the C language

You can use the strstr function:

Function name: strstr

Function: Find the first occurrence of a specified string in a string: char *strstr(char *str1, char *str2);

Example: include

#include

int main(void)

There shouldn't be a library function specifically for this, so it's good to make it up yourself, it's not complicated.

No way, right?

You have to write your own functions to do this.

Using some functions of string to implement, the algorithm is simple and clear, and it has been verified that you can directly copy and paste.

#include

#include

#include

#include

using namespace std;

void main()

Examples are as follows:

Direct compilation, arbitrary input strings and numbers in the program output result, the program execution result is shown in the following figure:

You can use the strncpy() function.

#include

char sub[20];

strncpy(sub,string+12,13) *copies the 13 digits in string starting with string[12] into sub*

If there is a special function for extracting a string of a specified length: strncpy(*s1,*s2,n);

If you extract m characters starting from n in a string, the procedure is as follows:

#include

#include

void main()

elseprintf("The length is out of range! ");

elseprintf("The starting position is out of range! ");

If you want to divide a piece of data into chunks in the C language, you can store it in chunks when reading the data, instead of reading it as a whole and then chunking it.

If the data is imported in other ways, it can only be stored on the hard disk, then read into memory, and then read in chunks by moving the file pointer.

Because the data store is stored in the whole block of memory, the memory (i.e., the data) cannot be directly chunked, and memcpy can only get the first part of the data.

Use a string to copy another string t, scan the string t from beginning to end, write string s for non-numeric characters as is, write a $ sign for numeric characters and then write the numeric character, and finally, add an end sign to the end of the s string. Use this method to sacrifice space, gain time.

#include

int fun(char *s)

For non-numeric characters, the string s* is written as-is

elses[j++]=t[i];

s[j]='\0';* add the end flag at the end of the string S * return 0;

int main()

Design Process:

Define two strings: s2, s2, and the character k

Enter any character k in the two strings s1, s2 and s1 to iterate through s1 to find the specified character k, record the current position starting from k character, and move the rest of the data back by the length of s2.

Copy S2 to the location where K is located.

Output s1. ** Below:

#include

#include

void main()

pos=i;Make a note of where you want to insert it.

len=strlen(s2);get the length of s2 for( i=strlen(s1); i>=pos;i-- Move the string backward.

Insert data. printf("%s", s1 );Output string}

Nonsense on the first floor, I told you to assign the s1 definition array, assign the initial value of the s2 definition array, and shift the array s3 containing s1 and s2, and the output of s3 is OK.

put"beijing"into an array of characters.

put"123"into another character array.

Before applying for a large enough array space, assign these two character values according to the following table.

Maybe it's easier to implement it with a linked list, here's the program with an array:

#include

#include

main()

n=strlen(b);

k=m;for(j=m+n;j>i;j--,k--)a[j]=a[k];

for(j=i,k=0;jprintf("%s",a);}

Stored in a char array (C C++ is supported).

char str="hello" ;

int i;

for( i=0;str[i];i++ printf("%c", str[i] ) refers to a character as an array: str[i].

for( i=0;*(str+i);i++ printf("%c", *str+i) ) Refer to a character as a pointer: *(str+i).

Stored in string (C++ only).

string str="abcde";

for(string::iterator iter = ; iter!=;iter++) uses iterators.

cout<<*iter<

The mistake is that when you judge the first non-@ character, it already outputs no character @ to exit the loop, so it won't detect @. Just change it to the following:

#include

#include

intmain()

Remember to prefix it with include

str[i];(i is where you want the character to be) include

#include

int main(void)

#include

define n x and change x to 1 if you want the first few

int main()

Any characters?

Random? Specify a location?

You can change the size of the array to suit your possible input situation.

#include

int main(){char str[200];Suppose you enter a 1-line string with a length of less than 200 char s[20][16]; Suppose there are about 20 comma-separated sections.

Each length should not exceed 16 characters and double d; Assuming that the number of data does not exceed 20 int i,j=0,l,n=0; fgets(str,200,stdin)。

Read in a line string with a newline character l = strlen(str).

You can use the strstr function:

Function name: strstr

Function: Find the first occurrence of a specified string in a string: char *strstr(char *str1, char *str2);

Example: include

#include

int main(void)