diff --git a/header/source.h b/header/source.h
index f04058d..1e5cd35 100644
--- a/header/source.h
+++ b/header/source.h
@@ -4,5 +4,6 @@
 
 int launchSource(int nombreMessage,int tailleMessage,int isTCP);
 int sendMultipleData(int nombreMessages, int tailleMessage, int sock, struct sockaddr_in socketStruct);
+void formatText(char * actualMessage, int num, int tailleMessage, char messageChar);
 
 #endif
\ No newline at end of file
diff --git a/header/tsock.h b/header/tsock.h
index 59708e0..334d3e6 100644
--- a/header/tsock.h
+++ b/header/tsock.h
@@ -1,16 +1,16 @@
 #ifndef HEADER_TSOCK
 #define HEADER_TSOCK
 
+#include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <netinet/in.h>
 #include <netdb.h>
-#include <stdio.h>
 #include <errno.h>
-#include <string.h>
 
 void setNbMessage(int * nb, int source);
 void printInfo(int nb, int source, int portNumber, char ipAddress[]);
diff --git a/src/main.c b/src/main.c
index 51c92aa..6e5186d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -8,7 +8,7 @@ int main (int argc, char **argv)
 	char *ipAddress;
 	extern char *optarg;
 	extern int optind;
-	int source = -1, nb_message = -1, c, tcp=1, port=9000, tailleMessage; /* Nb de messages à envoyer ou à recevoir, par défaut : 10 en émission, infini en réception */
+	int source = -1, nb_message = -1, c, tcp=1, port=9000, tailleMessage=-1; /* Nb de messages à envoyer ou à recevoir, par défaut : 10 en émission, infini en réception */
 	while ((c = getopt(argc, argv, "pn:sul:")) != -1) {
 		switch (c) {
 		case 'p':
@@ -45,6 +45,10 @@ int main (int argc, char **argv)
 		printf(usageChar);
 		exit(1);
 	}
+	if(tailleMessage == -1)
+	{
+		tailleMessage = 30;
+	}
 
 	getNonOtpArgs(argv, argc, port, &ipAddress);
 	setNbMessage(&nb_message,source);
diff --git a/src/source.c b/src/source.c
index 643c335..50df0c0 100644
--- a/src/source.c
+++ b/src/source.c
@@ -41,11 +41,31 @@ int sendMultipleData(int nombreMessages, int tailleMessage, int sock, struct soc
     char sendingMessage[tailleMessage];
     for(int i=0;i<nombreMessages;i++)
     {
-        memset(sendingMessage, messageChar, tailleMessage*sizeof(char)+1);
+        formatText(sendingMessage,i,tailleMessage,messageChar);
         longueurEmis=sendto(sock, sendingMessage, tailleMessage, 0, (struct sockaddr*)&socketStruct, sizeof(socketStruct));
         sendingMessage[tailleMessage]='\0';
         printf("Source\tEnvoi n°%d (%d) :\t[%s]\n",i+1,longueurEmis,sendingMessage);
-        messageChar++;
+        messageChar>='z'?messageChar='a':messageChar++;
     }
     return 0;
+}
+
+void formatText(char * actualMessage, int num, int tailleMessage, char messageChar)
+{
+    char numBuffer[15];
+    sprintf(numBuffer, "%d", (num+1)%10000);
+    int numberLength=0;
+    while(numBuffer[numberLength] != '\0')
+    {
+        numberLength++;
+    }
+    for(int i=0;i<4-numberLength;i++)
+    {
+        actualMessage[i]=0x20;
+    }
+    for(int i=4-numberLength,j=0;i<4;i++,j++)
+    {
+        actualMessage[i]=numBuffer[j];
+    }
+    memset(actualMessage+4, messageChar, tailleMessage);
 }
\ No newline at end of file