Question

我只是想从字符串中提取特定的单词我的节目是：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BUFFER_SIZE 100

int main() {

    FILE *f;
    char buffer[100];
    char buf[100];
    int count=0;
    char res[100];


  f=fopen("1JAC.pdb","rb");

while(fgets(buffer,BUFFER_SIZE,f))
{

if(strncmp(buffer,"ATOM",4)==0 && strncmp(buffer+13,"CA",2)==0 && strncmp(buffer+21,"A",1)==0)
{
strcpy(buf,buffer);

}

printf (buf);

该计划的输出是 ATOM 1033 CA LEU A 133 33.480 94.428 72.166 1.00 16.93 C

我只想提取单词＆＃34; LEU＆＃34;使用子字符串。我试过这样的事情：

Substring(17,3,buf);

但它不起作用...... 有人可以告诉我C中的子字符串。

Answer 1

Memcpy似乎是最好的方法......

memcpy( destBuff, sourceBuff + 17, 3 );
destBuff[ 3 ] = '\0';

请记住在需要时添加空终止符（正如我在示例中所做的那样）。

之前已经回答过这个问题，在Stack-overflow上已经多次了

（Get a substring of a char*）

Answer 2

//Use the following substring function,it will help you.
int main(int argc, char *argv[])
{

FILE *filepointer;
char string[1700];


filepointer=fopen("agg.txt", "r");

if (filepointer==NULL) 
{
        printf("Could not open data.txt!\n");
    return 1; 
}

while (fgets(string, sizeof(string), filepointer) != NULL) 
{   
    char* temp=substring(string,17,3);/*here 17 is the start position and 3 is the length of the string to be extracted*/ 
}

return 0;   
}




char *substring(char *string, int position, int length) 
{
char *pointer;
int c;
pointer = (char*) malloc(length+1);

if (pointer == NULL)
{
   printf("Unable to allocate memory.\n");
   exit(1);
}

 for (c = 0 ; c < length ; c++)
{
   *(pointer+c) = *(string+position-1);      
    string++;   
}

*(pointer+c) = '\0'; 
return pointer;
}

Answer 3

char out[4] = {0};
strncpy(out, buf+17, 3);

C编程中的子串

3 个答案: