Character String Manipulation

1. Character String Manipulation

2. Overview • Character string functions • sscanf() function • sprintf() function

3. 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 s1char *strchr(const char *s, int c); - Searches for first occurrence of c in sint strcmp(const char *s1, const char *s2); - Compares s1 to s2char *strcpy(char *s1, const char *s2); - Copies s2 onto s1size_t strlen(const char *s); - Returns the number of characters in schar *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

4. 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

5. 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

6. 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)

7. 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

8. Sample output Input data: 103 67.40 35 bottle Computation for Bin # 35: 103 bottle items * $ 67.40 per bottle = $ 6942.20