Character String Manipulation
Overview
• Character string functions
• sscanf() function
• sprintf() function
Some Character String Functions
double atof(const char *string);
- Converts string into a floating point value
int atoi(const char *string);
- Converts string into an int value
char *strcat(char *s1, const char *s2);
- Appends s2 onto the end of s1
char *strchr(const char *s, int c);
- Searches for first occurrence of c in s
int strcmp(const char *s1, const char *s2);
- Compares s1 to s2
char *strcpy(char *s1, const char *s2);
- Copies s2 onto s1
size_t strlen(const char *s);
- Returns the number of characters in s
char *strstr(const char *s1, const char *s2);
- Searches for s2 in s1
char *strtok(char *s1, const char *s2);
- Extracts tokens from string s1 based on token
separators in s2
sscanf() Function
• #include <stdio.h>
int sscanf(const char *buffer, const char *format, …);
• The sscanf() function is identical to scanf() except that data is read
from the array pointed to by buffer rather than stdin
• The return value is equal to the number of variables that were actually
assigned values
– A value of zero means that no fields were assigned any values
sprintf() Function
• #include <stdio.h>
int sprintf(char *buffer, const char *format, …);
• The sprintf() function is identical to printf() except that the output is
put into the array pointed to by buffer instead of being written to stdout
• The array pointed to by buffer should be null terminated
• The return value is equal to the number of characters actually placed into the
array
• The sprintf() function provides no bounds checking on the array pointed
to by buffer
Example use of strcpy(), sscanf()
and sprintf()
#include <stdio.h>
#define MAX_LENGTH 50
int main(void)
{
char stringA[MAX_LENGTH]";
char stringB[MAX_LENGTH];
int count;
float costPerItem;
int binNbr;
char name[MAX_LENGTH];
float totalCost;
(More on next slide)
Example use strcpy(), sscanf() and
sprintf()
strcpy(stringA, "103
67.4
35bottle“);
sscanf(stringA, "%d %f %d%s", &count, &costPerItem,
&binNbr, name);
fprintf(stderr, "Input data: %d %.2f %d %s\n\n",
count, costPerItem, binNbr, name);
totalCost = count * costPerItem;
sprintf(stringB, "%d %s items * $ %.2f per %s = $ %.2f",
count, name, costPerItem, name, totalCost);
printf("Computation for Bin # %d:\n %s\n", binNbr, stringB);
return 0;
} // End main
Sample output
Input data: 103 67.40 35 bottle
Computation for Bin # 35:
103 bottle items * $ 67.40 per bottle = $ 6942.20