parse a string for the required value - c

Question

I have a data as shown below, it contains the name of person and age respectively, her i have shown just 3 person names and the respective age, i can also have many names with respective age in that string.
I want to parse this string and store the name and corresponding age in a structure, can u please tell me how to parse this name and age. Ex: I want to get Allan 35 and store it in the below structure in name and age field respectively.So and forth for all the names present in that string.
How to parse the string, i tried strstr() but it was of no use for me. Pls can anyone tell how to parse this string.
struct data_base{
char *name;
int age;
};
char data[] = "Name Allan Age 35 Name John Age 50 Name Jim Age 20 ....."

Answer 1

You can use strtok to extract the tokens.

Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct data_base{
char *name;
int age;
};
#define NAME_TAG "Name "
#define AGE_TAG "Age "
char* getName(char **p){
int tag_size = strlen(NAME_TAG);
if(strncmp(*p, NAME_TAG, tag_size)==0){
char *agep = strstr(*p += tag_size, AGE_TAG);
int len = agep - *p -1;//-1: for space before "Age"
char *name = calloc(len + 1, sizeof(char));
strncpy(name, *p, len);
*p = agep;
return name;
}
return NULL;
}
int getAge(char **p){
int tag_size = strlen(AGE_TAG);
if(strncmp(*p, AGE_TAG, tag_size)==0){
int age = (int)strtol(*p += tag_size, p, 10);
if(**p == ' ')
*p += 1;
return age;
}
return -1;
}
struct data_base *parse(char *data, size_t *size){
char *p = data;
struct data_base *dbp=NULL;
*size = 0;
while(*p){
*size += 1;
dbp = realloc(dbp, sizeof(struct data_base)*(*size));
dbp[*size -1].name = getName(&p);//this is treated as format is correct
dbp[*size -1].age = getAge(&p);
}
return dbp;//realloc(dbp, sizeof(struct data_base)*(*size));
}
int main(void){
char data[] = "Name Allan Age 35 Name John Age 50 Name Jim Age 20";
struct data_base *dbp;
size_t i, size;
dbp = parse(data, &size);
//check print
for(i = 0; i < size ;++i){
printf("Name: %s, Age: %d\n", dbp[i].name, dbp[i].age);
}
//deallocate
return 0;
}

Answer 3

You might want to use sscanf. You'll need %s format for person's name and %d for age.

Answer 4

u can use two pointer to get the begin and end of a word,
use pointer p by strstr to get the place of "Name", then forth 5 to get the begin place of the name , then pointer q by strchr with space to get the end of the name, then you can use strncpy of snprintf to get the exactly name

Answer 5

Create function to handle each record, using sscanf().
// Scan string, return >0 if successful, 0 if done, else error code
int JZ_ScanDB(const char *data, int *Index, struct data_base *Dest) {
if (Dest) {
Dest->age = 0; // Form default answer
Dest->name = 0;
}
if (!data || !Index || !Dest) return -1; // Gremlins in your code
if ((*Index < 0) || (*Index > strlen(data))) return -2; // More gremlins
if (data[*Index] == '\0') return 0; // we are done
char Name[1000];
int retval = sscanf(&data[*Index], "Name %s Age %d %n", Name, &Dest->age, Index);
if (retval != 2) {
return -3;
}
Dest->name = strdup(Name);
return 0;
}
void DoIt() {
char data[] = "Name Allan Age 35 Name John Age 50 Name Jim Age 20";
int i = 0;
struct data_base Person;
int ret;
while ((ret = JZ_ScanDB(data, &i, &Person)) > 0) {
// do something with Person, watch for memory management
}
if (ret) {
// deal with unusual reason for stopping
}
}